€•ü      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ//translations/zh_CN/driver-api/dmaengine/client”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ//translations/zh_TW/driver-api/dmaengine/client”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ//translations/it_IT/driver-api/dmaengine/client”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ//translations/ja_JP/driver-api/dmaengine/client”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ//translations/ko_KR/driver-api/dmaengine/client”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ//translations/sp_SP/driver-api/dmaengine/client”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒDMA Engine API Guide”h]”hŒDMA Engine API Guide”…””}”(hh¨hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hh£hžhhŸŒI/var/lib/git/docbuild/linux/Documentation/driver-api/dmaengine/client.rst”h KubhŒ	paragraph”“”)”}”(hŒ(Vinod Koul <vinod dot koul at intel.com>”h]”hŒ(Vinod Koul <vinod dot koul at intel.com>”…””}”(hh¹hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubhŒnote”“”)”}”(hŒVFor DMA Engine usage in async_tx please see:
``Documentation/crypto/async-tx-api.rst``”h]”h¸)”}”(hŒVFor DMA Engine usage in async_tx please see:
``Documentation/crypto/async-tx-api.rst``”h]”(hŒ-For DMA Engine usage in async_tx please see:
”…””}”(hhÍhžhhŸNh NubhŒliteral”“”)”}”(hŒ)``Documentation/crypto/async-tx-api.rst``”h]”hŒ%Documentation/crypto/async-tx-api.rst”…””}”(hh×hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÕhhÍubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KhhÉubah}”(h]”h ]”h"]”h$]”h&]”uh1hÇhh£hžhhŸh¶h Nubh¸)”}”(hŒŽBelow is a guide to device driver writers on how to use the Slave-DMA API of the
DMA Engine. This is applicable only for slave DMA usage only.”h]”hŒŽBelow is a guide to device driver writers on how to use the Slave-DMA API of the
DMA Engine. This is applicable only for slave DMA usage only.”…””}”(hhñhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¢)”}”(hhh]”(h§)”}”(hŒ	DMA usage”h]”hŒ	DMA usage”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hhÿhžhhŸh¶h Kubh¸)”}”(hŒ0The slave DMA usage consists of following steps:”h]”hŒ0The slave DMA usage consists of following steps:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KhhÿhžhubhŒbullet_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hŒAllocate a DMA slave channel
”h]”h¸)”}”(hŒAllocate a DMA slave channel”h]”hŒAllocate a DMA slave channel”…””}”(hj)  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khj%  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj   hžhhŸh¶h Nubj$  )”}”(hŒ-Set slave and controller specific parameters
”h]”h¸)”}”(hŒ,Set slave and controller specific parameters”h]”hŒ,Set slave and controller specific parameters”…””}”(hjA  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khj=  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj   hžhhŸh¶h Nubj$  )”}”(hŒ!Get a descriptor for transaction
”h]”h¸)”}”(hŒ Get a descriptor for transaction”h]”hŒ Get a descriptor for transaction”…””}”(hjY  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KhjU  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj   hžhhŸh¶h Nubj$  )”}”(hŒSubmit the transaction
”h]”h¸)”}”(hŒSubmit the transaction”h]”hŒSubmit the transaction”…””}”(hjq  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khjm  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj   hžhhŸh¶h Nubj$  )”}”(hŒ:Issue pending requests and wait for callback notification
”h]”h¸)”}”(hŒ9Issue pending requests and wait for callback notification”h]”hŒ9Issue pending requests and wait for callback notification”…””}”(hj‰  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khj…  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj   hžhhŸh¶h Nubeh}”(h]”h ]”h"]”h$]”h&]”Œbullet”Œ-”uh1j  hŸh¶h Khhÿhžhubh¸)”}”(hŒ$The details of these operations are:”h]”hŒ$The details of these operations are:”…””}”(hj¥  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KhhÿhžhubhŒenumerated_list”“”)”}”(hhh]”(j$  )”}”(hXŸ  Allocate a DMA slave channel

Channel allocation is slightly different in the slave DMA context,
client drivers typically need a channel from a particular DMA
controller only and even in some cases a specific channel is desired.
To request a channel dma_request_chan() API is used.

Interface:

.. code-block:: c

   struct dma_chan *dma_request_chan(struct device *dev, const char *name);

Which will find and return the ``name`` DMA channel associated with the 'dev'
device. The association is done via DT, ACPI or board file based
dma_slave_map matching table.

A channel allocated via this interface is exclusive to the caller,
until dma_release_channel() is called.
”h]”(h¸)”}”(hŒAllocate a DMA slave channel”h]”hŒAllocate a DMA slave channel”…””}”(hj¼  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khj¸  ubh¸)”}”(hŒûChannel allocation is slightly different in the slave DMA context,
client drivers typically need a channel from a particular DMA
controller only and even in some cases a specific channel is desired.
To request a channel dma_request_chan() API is used.”h]”hŒûChannel allocation is slightly different in the slave DMA context,
client drivers typically need a channel from a particular DMA
controller only and even in some cases a specific channel is desired.
To request a channel dma_request_chan() API is used.”…””}”(hjÊ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K!hj¸  ubh¸)”}”(hŒ
Interface:”h]”hŒ
Interface:”…””}”(hjØ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K&hj¸  ubhŒliteral_block”“”)”}”(hŒHstruct dma_chan *dma_request_chan(struct device *dev, const char *name);”h]”hŒHstruct dma_chan *dma_request_chan(struct device *dev, const char *name);”…””}”hjè  sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”Œforce”‰Œlanguage”Œc”Œhighlight_args”}”uh1jæ  hŸh¶h K(hj¸  ubh¸)”}”(hŒ¬Which will find and return the ``name`` DMA channel associated with the 'dev'
device. The association is done via DT, ACPI or board file based
dma_slave_map matching table.”h]”(hŒWhich will find and return the ”…””}”(hjý  hžhhŸNh NubhÖ)”}”(hŒ``name``”h]”hŒname”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÕhjý  ubhŒ‰ DMA channel associated with the â€˜devâ€™
device. The association is done via DT, ACPI or board file based
dma_slave_map matching table.”…””}”(hjý  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K,hj¸  ubh¸)”}”(hŒiA channel allocated via this interface is exclusive to the caller,
until dma_release_channel() is called.”h]”hŒiA channel allocated via this interface is exclusive to the caller,
until dma_release_channel() is called.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K0hj¸  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjµ  hžhhŸh¶h Nubj$  )”}”(hXœ  Set slave and controller specific parameters

Next step is always to pass some specific information to the DMA
driver. Most of the generic information which a slave DMA can use
is in struct dma_slave_config. This allows the clients to specify
DMA direction, DMA addresses, bus widths, DMA burst lengths etc
for the peripheral.

If some DMA controllers have more parameters to be sent then they
should try to embed struct dma_slave_config in their controller
specific structure. That gives flexibility to client to pass more
parameters, if required.

Interface:

.. code-block:: c

   int dmaengine_slave_config(struct dma_chan *chan,
                     struct dma_slave_config *config)

Please see the dma_slave_config structure definition in dmaengine.h
for a detailed explanation of the struct members. Please note
that the 'direction' member will be going away as it duplicates the
direction given in the prepare call.
”h]”(h¸)”}”(hŒ,Set slave and controller specific parameters”h]”hŒ,Set slave and controller specific parameters”…””}”(hj5  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K3hj1  ubh¸)”}”(hX  Next step is always to pass some specific information to the DMA
driver. Most of the generic information which a slave DMA can use
is in struct dma_slave_config. This allows the clients to specify
DMA direction, DMA addresses, bus widths, DMA burst lengths etc
for the peripheral.”h]”hX  Next step is always to pass some specific information to the DMA
driver. Most of the generic information which a slave DMA can use
is in struct dma_slave_config. This allows the clients to specify
DMA direction, DMA addresses, bus widths, DMA burst lengths etc
for the peripheral.”…””}”(hjC  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K5hj1  ubh¸)”}”(hŒÜIf some DMA controllers have more parameters to be sent then they
should try to embed struct dma_slave_config in their controller
specific structure. That gives flexibility to client to pass more
parameters, if required.”h]”hŒÜIf some DMA controllers have more parameters to be sent then they
should try to embed struct dma_slave_config in their controller
specific structure. That gives flexibility to client to pass more
parameters, if required.”…””}”(hjQ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K;hj1  ubh¸)”}”(hŒ
Interface:”h]”hŒ
Interface:”…””}”(hj_  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K@hj1  ubjç  )”}”(hŒdint dmaengine_slave_config(struct dma_chan *chan,
                  struct dma_slave_config *config)”h]”hŒdint dmaengine_slave_config(struct dma_chan *chan,
                  struct dma_slave_config *config)”…””}”hjm  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h KBhj1  ubh¸)”}”(hŒêPlease see the dma_slave_config structure definition in dmaengine.h
for a detailed explanation of the struct members. Please note
that the 'direction' member will be going away as it duplicates the
direction given in the prepare call.”h]”hŒîPlease see the dma_slave_config structure definition in dmaengine.h
for a detailed explanation of the struct members. Please note
that the â€˜directionâ€™ member will be going away as it duplicates the
direction given in the prepare call.”…””}”(hj|  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KGhj1  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjµ  hžhhŸh¶h Nubj$  )”}”(hŒ!Get a descriptor for transaction
”h]”h¸)”}”(hŒ Get a descriptor for transaction”h]”hŒ Get a descriptor for transaction”…””}”(hj”  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KLhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjµ  hžhhŸh¶h Nubeh}”(h]”h ]”h"]”h$]”h&]”Œenumtype”Œarabic”Œprefix”hŒsuffix”Œ.”uh1j³  hhÿhžhhŸh¶h KubhŒblock_quote”“”)”}”(hXJ  For slave usage the various modes of slave transfers supported by the
DMA-engine are:

- slave_sg: DMA a list of scatter gather buffers from/to a peripheral

- peripheral_dma_vec: DMA an array of scatter gather buffers from/to a
  peripheral. Similar to slave_sg, but uses an array of dma_vec
  structures instead of a scatterlist.

- dma_cyclic: Perform a cyclic DMA operation from/to a peripheral till the
  operation is explicitly stopped.

- interleaved_dma: This is common to Slave as well as M2M clients. For slave
  address of devices' fifo could be already known to the driver.
  Various types of operations could be expressed by setting
  appropriate values to the 'dma_interleaved_template' members. Cyclic
  interleaved DMA transfers are also possible if supported by the channel by
  setting the DMA_PREP_REPEAT transfer flag.

A non-NULL return of this transfer API represents a "descriptor" for
the given transaction.

Interface:

.. code-block:: c

   struct dma_async_tx_descriptor *dmaengine_prep_slave_sg(
              struct dma_chan *chan, struct scatterlist *sgl,
              unsigned int sg_len, enum dma_data_direction direction,
              unsigned long flags);

   struct dma_async_tx_descriptor *dmaengine_prep_peripheral_dma_vec(
              struct dma_chan *chan, const struct dma_vec *vecs,
              size_t nents, enum dma_data_direction direction,
              unsigned long flags);

   struct dma_async_tx_descriptor *dmaengine_prep_dma_cyclic(
              struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
              size_t period_len, enum dma_data_direction direction);

   struct dma_async_tx_descriptor *dmaengine_prep_interleaved_dma(
              struct dma_chan *chan, struct dma_interleaved_template *xt,
              unsigned long flags);

The peripheral driver is expected to have mapped the scatterlist for
the DMA operation prior to calling dmaengine_prep_slave_sg(), and must
keep the scatterlist mapped until the DMA operation has completed.
The scatterlist must be mapped using the DMA struct device.
If a mapping needs to be synchronized later, dma_sync_*_for_*() must be
called using the DMA struct device, too.
So, normal setup should look like this:

.. code-block:: c

   struct device *dma_dev = dmaengine_get_dma_device(chan);

   nr_sg = dma_map_sg(dma_dev, sgl, sg_len);
      if (nr_sg == 0)
              /* error */

      desc = dmaengine_prep_slave_sg(chan, sgl, nr_sg, direction, flags);

Once a descriptor has been obtained, the callback information can be
added and the descriptor must then be submitted. Some DMA engine
drivers may hold a spinlock between a successful preparation and
submission so it is important that these two operations are closely
paired.

.. note::

   Although the async_tx API specifies that completion callback
   routines cannot submit any new operations, this is not the
   case for slave/cyclic DMA.

   For slave DMA, the subsequent transaction may not be available
   for submission prior to callback function being invoked, so
   slave DMA callbacks are permitted to prepare and submit a new
   transaction.

   For cyclic DMA, a callback function may wish to terminate the
   DMA via dmaengine_terminate_async().

   Therefore, it is important that DMA engine drivers drop any
   locks before calling the callback function which may cause a
   deadlock.

   Note that callbacks will always be invoked from the DMA
   engines tasklet, never from interrupt context.

**Optional: per descriptor metadata**

DMAengine provides two ways for metadata support.

DESC_METADATA_CLIENT

  The metadata buffer is allocated/provided by the client driver and it is
  attached to the descriptor.

.. code-block:: c

   int dmaengine_desc_attach_metadata(struct dma_async_tx_descriptor *desc,
                                 void *data, size_t len);

DESC_METADATA_ENGINE

  The metadata buffer is allocated/managed by the DMA driver. The client
  driver can ask for the pointer, maximum size and the currently used size of
  the metadata and can directly update or read it.

  Because the DMA driver manages the memory area containing the metadata,
  clients must make sure that they do not try to access or get the pointer
  after their transfer completion callback has run for the descriptor.
  If no completion callback has been defined for the transfer, then the
  metadata must not be accessed after issue_pending.
  In other words: if the aim is to read back metadata after the transfer is
  completed, then the client must use completion callback.

.. code-block:: c

   void *dmaengine_desc_get_metadata_ptr(struct dma_async_tx_descriptor *desc,
              size_t *payload_len, size_t *max_len);

   int dmaengine_desc_set_metadata_len(struct dma_async_tx_descriptor *desc,
              size_t payload_len);

Client drivers can query if a given mode is supported with:

.. code-block:: c

   bool dmaengine_is_metadata_mode_supported(struct dma_chan *chan,
              enum dma_desc_metadata_mode mode);

Depending on the used mode client drivers must follow different flow.

DESC_METADATA_CLIENT

  - DMA_MEM_TO_DEV / DEV_MEM_TO_MEM:

    1. prepare the descriptor (dmaengine_prep_*)
       construct the metadata in the client's buffer
    2. use dmaengine_desc_attach_metadata() to attach the buffer to the
       descriptor
    3. submit the transfer

  - DMA_DEV_TO_MEM:

    1. prepare the descriptor (dmaengine_prep_*)
    2. use dmaengine_desc_attach_metadata() to attach the buffer to the
       descriptor
    3. submit the transfer
    4. when the transfer is completed, the metadata should be available in the
       attached buffer

DESC_METADATA_ENGINE

  - DMA_MEM_TO_DEV / DEV_MEM_TO_MEM:

    1. prepare the descriptor (dmaengine_prep_*)
    2. use dmaengine_desc_get_metadata_ptr() to get the pointer to the
       engine's metadata area
    3. update the metadata at the pointer
    4. use dmaengine_desc_set_metadata_len()  to tell the DMA engine the
       amount of data the client has placed into the metadata buffer
    5. submit the transfer

  - DMA_DEV_TO_MEM:

    1. prepare the descriptor (dmaengine_prep_*)
    2. submit the transfer
    3. on transfer completion, use dmaengine_desc_get_metadata_ptr() to get
       the pointer to the engine's metadata area
    4. read out the metadata from the pointer

.. note::

   When DESC_METADATA_ENGINE mode is used the metadata area for the descriptor
   is no longer valid after the transfer has been completed (valid up to the
   point when the completion callback returns if used).

   Mixed use of DESC_METADATA_CLIENT / DESC_METADATA_ENGINE is not allowed,
   client drivers must use either of the modes per descriptor.
”h]”(h¸)”}”(hŒUFor slave usage the various modes of slave transfers supported by the
DMA-engine are:”h]”hŒUFor slave usage the various modes of slave transfers supported by the
DMA-engine are:”…””}”(hj¹  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KNhjµ  ubj  )”}”(hhh]”(j$  )”}”(hŒDslave_sg: DMA a list of scatter gather buffers from/to a peripheral
”h]”h¸)”}”(hŒCslave_sg: DMA a list of scatter gather buffers from/to a peripheral”h]”hŒCslave_sg: DMA a list of scatter gather buffers from/to a peripheral”…””}”(hjÎ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KQhjÊ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjÇ  ubj$  )”}”(hŒ¨peripheral_dma_vec: DMA an array of scatter gather buffers from/to a
peripheral. Similar to slave_sg, but uses an array of dma_vec
structures instead of a scatterlist.
”h]”h¸)”}”(hŒ§peripheral_dma_vec: DMA an array of scatter gather buffers from/to a
peripheral. Similar to slave_sg, but uses an array of dma_vec
structures instead of a scatterlist.”h]”hŒ§peripheral_dma_vec: DMA an array of scatter gather buffers from/to a
peripheral. Similar to slave_sg, but uses an array of dma_vec
structures instead of a scatterlist.”…””}”(hjæ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KShjâ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjÇ  ubj$  )”}”(hŒjdma_cyclic: Perform a cyclic DMA operation from/to a peripheral till the
operation is explicitly stopped.
”h]”h¸)”}”(hŒidma_cyclic: Perform a cyclic DMA operation from/to a peripheral till the
operation is explicitly stopped.”h]”hŒidma_cyclic: Perform a cyclic DMA operation from/to a peripheral till the
operation is explicitly stopped.”…””}”(hjþ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KWhjú  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjÇ  ubj$  )”}”(hX  interleaved_dma: This is common to Slave as well as M2M clients. For slave
address of devices' fifo could be already known to the driver.
Various types of operations could be expressed by setting
appropriate values to the 'dma_interleaved_template' members. Cyclic
interleaved DMA transfers are also possible if supported by the channel by
setting the DMA_PREP_REPEAT transfer flag.
”h]”h¸)”}”(hX~  interleaved_dma: This is common to Slave as well as M2M clients. For slave
address of devices' fifo could be already known to the driver.
Various types of operations could be expressed by setting
appropriate values to the 'dma_interleaved_template' members. Cyclic
interleaved DMA transfers are also possible if supported by the channel by
setting the DMA_PREP_REPEAT transfer flag.”h]”hX„  interleaved_dma: This is common to Slave as well as M2M clients. For slave
address of devicesâ€™ fifo could be already known to the driver.
Various types of operations could be expressed by setting
appropriate values to the â€˜dma_interleaved_templateâ€™ members. Cyclic
interleaved DMA transfers are also possible if supported by the channel by
setting the DMA_PREP_REPEAT transfer flag.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KZhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjÇ  ubeh}”(h]”h ]”h"]”h$]”h&]”j£  j¤  uh1j  hŸh¶h KQhjµ  ubh¸)”}”(hŒ[A non-NULL return of this transfer API represents a "descriptor" for
the given transaction.”h]”hŒ_A non-NULL return of this transfer API represents a â€œdescriptorâ€ for
the given transaction.”…””}”(hj0  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kahjµ  ubh¸)”}”(hŒ
Interface:”h]”hŒ
Interface:”…””}”(hj>  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kdhjµ  ubjç  )”}”(hX$  struct dma_async_tx_descriptor *dmaengine_prep_slave_sg(
           struct dma_chan *chan, struct scatterlist *sgl,
           unsigned int sg_len, enum dma_data_direction direction,
           unsigned long flags);

struct dma_async_tx_descriptor *dmaengine_prep_peripheral_dma_vec(
           struct dma_chan *chan, const struct dma_vec *vecs,
           size_t nents, enum dma_data_direction direction,
           unsigned long flags);

struct dma_async_tx_descriptor *dmaengine_prep_dma_cyclic(
           struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
           size_t period_len, enum dma_data_direction direction);

struct dma_async_tx_descriptor *dmaengine_prep_interleaved_dma(
           struct dma_chan *chan, struct dma_interleaved_template *xt,
           unsigned long flags);”h]”hX$  struct dma_async_tx_descriptor *dmaengine_prep_slave_sg(
           struct dma_chan *chan, struct scatterlist *sgl,
           unsigned int sg_len, enum dma_data_direction direction,
           unsigned long flags);

struct dma_async_tx_descriptor *dmaengine_prep_peripheral_dma_vec(
           struct dma_chan *chan, const struct dma_vec *vecs,
           size_t nents, enum dma_data_direction direction,
           unsigned long flags);

struct dma_async_tx_descriptor *dmaengine_prep_dma_cyclic(
           struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
           size_t period_len, enum dma_data_direction direction);

struct dma_async_tx_descriptor *dmaengine_prep_interleaved_dma(
           struct dma_chan *chan, struct dma_interleaved_template *xt,
           unsigned long flags);”…””}”hjL  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h Kfhjµ  ubh¸)”}”(hX£  The peripheral driver is expected to have mapped the scatterlist for
the DMA operation prior to calling dmaengine_prep_slave_sg(), and must
keep the scatterlist mapped until the DMA operation has completed.
The scatterlist must be mapped using the DMA struct device.
If a mapping needs to be synchronized later, dma_sync_*_for_*() must be
called using the DMA struct device, too.
So, normal setup should look like this:”h]”hX£  The peripheral driver is expected to have mapped the scatterlist for
the DMA operation prior to calling dmaengine_prep_slave_sg(), and must
keep the scatterlist mapped until the DMA operation has completed.
The scatterlist must be mapped using the DMA struct device.
If a mapping needs to be synchronized later, dma_sync_*_for_*() must be
called using the DMA struct device, too.
So, normal setup should look like this:”…””}”(hj[  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kzhjµ  ubjç  )”}”(hŒÕstruct device *dma_dev = dmaengine_get_dma_device(chan);

nr_sg = dma_map_sg(dma_dev, sgl, sg_len);
   if (nr_sg == 0)
           /* error */

   desc = dmaengine_prep_slave_sg(chan, sgl, nr_sg, direction, flags);”h]”hŒÕstruct device *dma_dev = dmaengine_get_dma_device(chan);

nr_sg = dma_map_sg(dma_dev, sgl, sg_len);
   if (nr_sg == 0)
           /* error */

   desc = dmaengine_prep_slave_sg(chan, sgl, nr_sg, direction, flags);”…””}”hji  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h K‚hjµ  ubh¸)”}”(hX  Once a descriptor has been obtained, the callback information can be
added and the descriptor must then be submitted. Some DMA engine
drivers may hold a spinlock between a successful preparation and
submission so it is important that these two operations are closely
paired.”h]”hX  Once a descriptor has been obtained, the callback information can be
added and the descriptor must then be submitted. Some DMA engine
drivers may hold a spinlock between a successful preparation and
submission so it is important that these two operations are closely
paired.”…””}”(hjx  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KŒhjµ  ubhÈ)”}”(hX©  Although the async_tx API specifies that completion callback
routines cannot submit any new operations, this is not the
case for slave/cyclic DMA.

For slave DMA, the subsequent transaction may not be available
for submission prior to callback function being invoked, so
slave DMA callbacks are permitted to prepare and submit a new
transaction.

For cyclic DMA, a callback function may wish to terminate the
DMA via dmaengine_terminate_async().

Therefore, it is important that DMA engine drivers drop any
locks before calling the callback function which may cause a
deadlock.

Note that callbacks will always be invoked from the DMA
engines tasklet, never from interrupt context.”h]”(h¸)”}”(hŒ’Although the async_tx API specifies that completion callback
routines cannot submit any new operations, this is not the
case for slave/cyclic DMA.”h]”hŒ’Although the async_tx API specifies that completion callback
routines cannot submit any new operations, this is not the
case for slave/cyclic DMA.”…””}”(hjŠ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K”hj†  ubh¸)”}”(hŒÅFor slave DMA, the subsequent transaction may not be available
for submission prior to callback function being invoked, so
slave DMA callbacks are permitted to prepare and submit a new
transaction.”h]”hŒÅFor slave DMA, the subsequent transaction may not be available
for submission prior to callback function being invoked, so
slave DMA callbacks are permitted to prepare and submit a new
transaction.”…””}”(hj˜  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K˜hj†  ubh¸)”}”(hŒbFor cyclic DMA, a callback function may wish to terminate the
DMA via dmaengine_terminate_async().”h]”hŒbFor cyclic DMA, a callback function may wish to terminate the
DMA via dmaengine_terminate_async().”…””}”(hj¦  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khj†  ubh¸)”}”(hŒ‚Therefore, it is important that DMA engine drivers drop any
locks before calling the callback function which may cause a
deadlock.”h]”hŒ‚Therefore, it is important that DMA engine drivers drop any
locks before calling the callback function which may cause a
deadlock.”…””}”(hj´  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K hj†  ubh¸)”}”(hŒfNote that callbacks will always be invoked from the DMA
engines tasklet, never from interrupt context.”h]”hŒfNote that callbacks will always be invoked from the DMA
engines tasklet, never from interrupt context.”…””}”(hjÂ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K¤hj†  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÇhjµ  ubh¸)”}”(hŒ%**Optional: per descriptor metadata**”h]”hŒstrong”“”)”}”(hjØ  h]”hŒ!Optional: per descriptor metadata”…””}”(hjÜ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÚ  hjÖ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K§hjµ  ubh¸)”}”(hŒ1DMAengine provides two ways for metadata support.”h]”hŒ1DMAengine provides two ways for metadata support.”…””}”(hjï  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K©hjµ  ubh¸)”}”(hŒDESC_METADATA_CLIENT”h]”hŒDESC_METADATA_CLIENT”…””}”(hjý  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K«hjµ  ubj´  )”}”(hŒeThe metadata buffer is allocated/provided by the client driver and it is
attached to the descriptor.
”h]”h¸)”}”(hŒdThe metadata buffer is allocated/provided by the client driver and it is
attached to the descriptor.”h]”hŒdThe metadata buffer is allocated/provided by the client driver and it is
attached to the descriptor.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K­hj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j³  hŸh¶h K­hjµ  ubjç  )”}”(hŒint dmaengine_desc_attach_metadata(struct dma_async_tx_descriptor *desc,
                              void *data, size_t len);”h]”hŒint dmaengine_desc_attach_metadata(struct dma_async_tx_descriptor *desc,
                              void *data, size_t len);”…””}”hj#  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h K°hjµ  ubh¸)”}”(hŒDESC_METADATA_ENGINE”h]”hŒDESC_METADATA_ENGINE”…””}”(hj2  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kµhjµ  ubj´  )”}”(hX—  The metadata buffer is allocated/managed by the DMA driver. The client
driver can ask for the pointer, maximum size and the currently used size of
the metadata and can directly update or read it.

Because the DMA driver manages the memory area containing the metadata,
clients must make sure that they do not try to access or get the pointer
after their transfer completion callback has run for the descriptor.
If no completion callback has been defined for the transfer, then the
metadata must not be accessed after issue_pending.
In other words: if the aim is to read back metadata after the transfer is
completed, then the client must use completion callback.
”h]”(h¸)”}”(hŒÃThe metadata buffer is allocated/managed by the DMA driver. The client
driver can ask for the pointer, maximum size and the currently used size of
the metadata and can directly update or read it.”h]”hŒÃThe metadata buffer is allocated/managed by the DMA driver. The client
driver can ask for the pointer, maximum size and the currently used size of
the metadata and can directly update or read it.”…””}”(hjD  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K·hj@  ubh¸)”}”(hXÑ  Because the DMA driver manages the memory area containing the metadata,
clients must make sure that they do not try to access or get the pointer
after their transfer completion callback has run for the descriptor.
If no completion callback has been defined for the transfer, then the
metadata must not be accessed after issue_pending.
In other words: if the aim is to read back metadata after the transfer is
completed, then the client must use completion callback.”h]”hXÑ  Because the DMA driver manages the memory area containing the metadata,
clients must make sure that they do not try to access or get the pointer
after their transfer completion callback has run for the descriptor.
If no completion callback has been defined for the transfer, then the
metadata must not be accessed after issue_pending.
In other words: if the aim is to read back metadata after the transfer is
completed, then the client must use completion callback.”…””}”(hjR  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K»hj@  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j³  hŸh¶h K·hjµ  ubjç  )”}”(hŒèvoid *dmaengine_desc_get_metadata_ptr(struct dma_async_tx_descriptor *desc,
           size_t *payload_len, size_t *max_len);

int dmaengine_desc_set_metadata_len(struct dma_async_tx_descriptor *desc,
           size_t payload_len);”h]”hŒèvoid *dmaengine_desc_get_metadata_ptr(struct dma_async_tx_descriptor *desc,
           size_t *payload_len, size_t *max_len);

int dmaengine_desc_set_metadata_len(struct dma_async_tx_descriptor *desc,
           size_t payload_len);”…””}”hjf  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h KÃhjµ  ubh¸)”}”(hŒ;Client drivers can query if a given mode is supported with:”h]”hŒ;Client drivers can query if a given mode is supported with:”…””}”(hju  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KËhjµ  ubjç  )”}”(hŒnbool dmaengine_is_metadata_mode_supported(struct dma_chan *chan,
           enum dma_desc_metadata_mode mode);”h]”hŒnbool dmaengine_is_metadata_mode_supported(struct dma_chan *chan,
           enum dma_desc_metadata_mode mode);”…””}”hjƒ  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h KÍhjµ  ubh¸)”}”(hŒEDepending on the used mode client drivers must follow different flow.”h]”hŒEDepending on the used mode client drivers must follow different flow.”…””}”(hj’  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KÒhjµ  ubh¸)”}”(hŒDESC_METADATA_CLIENT”h]”hŒDESC_METADATA_CLIENT”…””}”(hj   hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KÔhjµ  ubj´  )”}”(hX	  - DMA_MEM_TO_DEV / DEV_MEM_TO_MEM:

  1. prepare the descriptor (dmaengine_prep_*)
     construct the metadata in the client's buffer
  2. use dmaengine_desc_attach_metadata() to attach the buffer to the
     descriptor
  3. submit the transfer

- DMA_DEV_TO_MEM:

  1. prepare the descriptor (dmaengine_prep_*)
  2. use dmaengine_desc_attach_metadata() to attach the buffer to the
     descriptor
  3. submit the transfer
  4. when the transfer is completed, the metadata should be available in the
     attached buffer
”h]”j  )”}”(hhh]”(j$  )”}”(hŒéDMA_MEM_TO_DEV / DEV_MEM_TO_MEM:

1. prepare the descriptor (dmaengine_prep_*)
   construct the metadata in the client's buffer
2. use dmaengine_desc_attach_metadata() to attach the buffer to the
   descriptor
3. submit the transfer
”h]”(h¸)”}”(hŒ DMA_MEM_TO_DEV / DEV_MEM_TO_MEM:”h]”hŒ DMA_MEM_TO_DEV / DEV_MEM_TO_MEM:”…””}”(hj¹  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KÖhjµ  ubj´  )”}”(hhh]”(j$  )”}”(hŒWprepare the descriptor (dmaengine_prep_*)
construct the metadata in the client's buffer”h]”h¸)”}”(hŒWprepare the descriptor (dmaengine_prep_*)
construct the metadata in the client's buffer”h]”hŒYprepare the descriptor (dmaengine_prep_*)
construct the metadata in the clientâ€™s buffer”…””}”(hjÎ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KØhjÊ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjÇ  ubj$  )”}”(hŒKuse dmaengine_desc_attach_metadata() to attach the buffer to the
descriptor”h]”h¸)”}”(hŒKuse dmaengine_desc_attach_metadata() to attach the buffer to the
descriptor”h]”hŒKuse dmaengine_desc_attach_metadata() to attach the buffer to the
descriptor”…””}”(hjæ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KÚhjâ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjÇ  ubj$  )”}”(hŒsubmit the transfer
”h]”h¸)”}”(hŒsubmit the transfer”h]”hŒsubmit the transfer”…””}”(hjþ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KÜhjú  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjÇ  ubeh}”(h]”h ]”h"]”h$]”h&]”j®  j¯  j°  hj±  j²  uh1j³  hjµ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj²  ubj$  )”}”(hX  DMA_DEV_TO_MEM:

1. prepare the descriptor (dmaengine_prep_*)
2. use dmaengine_desc_attach_metadata() to attach the buffer to the
   descriptor
3. submit the transfer
4. when the transfer is completed, the metadata should be available in the
   attached buffer
”h]”(h¸)”}”(hŒDMA_DEV_TO_MEM:”h]”hŒDMA_DEV_TO_MEM:”…””}”(hj"  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KÞhj  ubj´  )”}”(hhh]”(j$  )”}”(hŒ)prepare the descriptor (dmaengine_prep_*)”h]”h¸)”}”(hj5  h]”hŒ)prepare the descriptor (dmaengine_prep_*)”…””}”(hj7  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kàhj3  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj0  ubj$  )”}”(hŒKuse dmaengine_desc_attach_metadata() to attach the buffer to the
descriptor”h]”h¸)”}”(hŒKuse dmaengine_desc_attach_metadata() to attach the buffer to the
descriptor”h]”hŒKuse dmaengine_desc_attach_metadata() to attach the buffer to the
descriptor”…””}”(hjN  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KáhjJ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj0  ubj$  )”}”(hŒsubmit the transfer”h]”h¸)”}”(hjd  h]”hŒsubmit the transfer”…””}”(hjf  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kãhjb  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj0  ubj$  )”}”(hŒXwhen the transfer is completed, the metadata should be available in the
attached buffer
”h]”h¸)”}”(hŒWwhen the transfer is completed, the metadata should be available in the
attached buffer”h]”hŒWwhen the transfer is completed, the metadata should be available in the
attached buffer”…””}”(hj}  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kähjy  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj0  ubeh}”(h]”h ]”h"]”h$]”h&]”j®  j¯  j°  hj±  j²  uh1j³  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj²  ubeh}”(h]”h ]”h"]”h$]”h&]”j£  j¤  uh1j  hŸh¶h KÖhj®  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j³  hŸh¶h KÖhjµ  ubh¸)”}”(hŒDESC_METADATA_ENGINE”h]”hŒDESC_METADATA_ENGINE”…””}”(hj©  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kçhjµ  ubj´  )”}”(hX€  - DMA_MEM_TO_DEV / DEV_MEM_TO_MEM:

  1. prepare the descriptor (dmaengine_prep_*)
  2. use dmaengine_desc_get_metadata_ptr() to get the pointer to the
     engine's metadata area
  3. update the metadata at the pointer
  4. use dmaengine_desc_set_metadata_len()  to tell the DMA engine the
     amount of data the client has placed into the metadata buffer
  5. submit the transfer

- DMA_DEV_TO_MEM:

  1. prepare the descriptor (dmaengine_prep_*)
  2. submit the transfer
  3. on transfer completion, use dmaengine_desc_get_metadata_ptr() to get
     the pointer to the engine's metadata area
  4. read out the metadata from the pointer
”h]”j  )”}”(hhh]”(j$  )”}”(hXo  DMA_MEM_TO_DEV / DEV_MEM_TO_MEM:

1. prepare the descriptor (dmaengine_prep_*)
2. use dmaengine_desc_get_metadata_ptr() to get the pointer to the
   engine's metadata area
3. update the metadata at the pointer
4. use dmaengine_desc_set_metadata_len()  to tell the DMA engine the
   amount of data the client has placed into the metadata buffer
5. submit the transfer
”h]”(h¸)”}”(hŒ DMA_MEM_TO_DEV / DEV_MEM_TO_MEM:”h]”hŒ DMA_MEM_TO_DEV / DEV_MEM_TO_MEM:”…””}”(hjÂ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kéhj¾  ubj´  )”}”(hhh]”(j$  )”}”(hŒ)prepare the descriptor (dmaengine_prep_*)”h]”h¸)”}”(hjÕ  h]”hŒ)prepare the descriptor (dmaengine_prep_*)”…””}”(hj×  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KëhjÓ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjÐ  ubj$  )”}”(hŒVuse dmaengine_desc_get_metadata_ptr() to get the pointer to the
engine's metadata area”h]”h¸)”}”(hŒVuse dmaengine_desc_get_metadata_ptr() to get the pointer to the
engine's metadata area”h]”hŒXuse dmaengine_desc_get_metadata_ptr() to get the pointer to the
engineâ€™s metadata area”…””}”(hjî  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kìhjê  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjÐ  ubj$  )”}”(hŒ"update the metadata at the pointer”h]”h¸)”}”(hj  h]”hŒ"update the metadata at the pointer”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kîhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjÐ  ubj$  )”}”(hŒuse dmaengine_desc_set_metadata_len()  to tell the DMA engine the
amount of data the client has placed into the metadata buffer”h]”h¸)”}”(hŒuse dmaengine_desc_set_metadata_len()  to tell the DMA engine the
amount of data the client has placed into the metadata buffer”h]”hŒuse dmaengine_desc_set_metadata_len()  to tell the DMA engine the
amount of data the client has placed into the metadata buffer”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kïhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjÐ  ubj$  )”}”(hŒsubmit the transfer
”h]”h¸)”}”(hŒsubmit the transfer”h]”hŒsubmit the transfer”…””}”(hj5  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kñhj1  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjÐ  ubeh}”(h]”h ]”h"]”h$]”h&]”j®  j¯  j°  hj±  j²  uh1j³  hj¾  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj»  ubj$  )”}”(hŒôDMA_DEV_TO_MEM:

1. prepare the descriptor (dmaengine_prep_*)
2. submit the transfer
3. on transfer completion, use dmaengine_desc_get_metadata_ptr() to get
   the pointer to the engine's metadata area
4. read out the metadata from the pointer
”h]”(h¸)”}”(hŒDMA_DEV_TO_MEM:”h]”hŒDMA_DEV_TO_MEM:”…””}”(hjY  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KóhjU  ubj´  )”}”(hhh]”(j$  )”}”(hŒ)prepare the descriptor (dmaengine_prep_*)”h]”h¸)”}”(hjl  h]”hŒ)prepare the descriptor (dmaengine_prep_*)”…””}”(hjn  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kõhjj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjg  ubj$  )”}”(hŒsubmit the transfer”h]”h¸)”}”(hjƒ  h]”hŒsubmit the transfer”…””}”(hj…  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Köhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjg  ubj$  )”}”(hŒnon transfer completion, use dmaengine_desc_get_metadata_ptr() to get
the pointer to the engine's metadata area”h]”h¸)”}”(hŒnon transfer completion, use dmaengine_desc_get_metadata_ptr() to get
the pointer to the engine's metadata area”h]”hŒpon transfer completion, use dmaengine_desc_get_metadata_ptr() to get
the pointer to the engineâ€™s metadata area”…””}”(hjœ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K÷hj˜  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjg  ubj$  )”}”(hŒ'read out the metadata from the pointer
”h]”h¸)”}”(hŒ&read out the metadata from the pointer”h]”hŒ&read out the metadata from the pointer”…””}”(hj´  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kùhj°  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j#  hjg  ubeh}”(h]”h ]”h"]”h$]”h&]”j®  j¯  j°  hj±  j²  uh1j³  hjU  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj»  ubeh}”(h]”h ]”h"]”h$]”h&]”j£  j¤  uh1j  hŸh¶h Kéhj·  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j³  hŸh¶h Kéhjµ  ubhÈ)”}”(hXP  When DESC_METADATA_ENGINE mode is used the metadata area for the descriptor
is no longer valid after the transfer has been completed (valid up to the
point when the completion callback returns if used).

Mixed use of DESC_METADATA_CLIENT / DESC_METADATA_ENGINE is not allowed,
client drivers must use either of the modes per descriptor.”h]”(h¸)”}”(hŒÊWhen DESC_METADATA_ENGINE mode is used the metadata area for the descriptor
is no longer valid after the transfer has been completed (valid up to the
point when the completion callback returns if used).”h]”hŒÊWhen DESC_METADATA_ENGINE mode is used the metadata area for the descriptor
is no longer valid after the transfer has been completed (valid up to the
point when the completion callback returns if used).”…””}”(hjä  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kýhjà  ubh¸)”}”(hŒ„Mixed use of DESC_METADATA_CLIENT / DESC_METADATA_ENGINE is not allowed,
client drivers must use either of the modes per descriptor.”h]”hŒ„Mixed use of DESC_METADATA_CLIENT / DESC_METADATA_ENGINE is not allowed,
client drivers must use either of the modes per descriptor.”…””}”(hjò  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Mhjà  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÇhjµ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j³  hŸh¶h KNhhÿhžhubj´  )”}”(hhh]”(j$  )”}”(hX  Submit the transaction

Once the descriptor has been prepared and the callback information
added, it must be placed on the DMA engine drivers pending queue.

Interface:

.. code-block:: c

   dma_cookie_t dmaengine_submit(struct dma_async_tx_descriptor *desc)

This returns a cookie can be used to check the progress of DMA engine
activity via other DMA engine calls not covered in this document.

dmaengine_submit() will not start the DMA operation, it merely adds
it to the pending queue. For this, see step 5, dma_async_issue_pending.

.. note::

   After calling ``dmaengine_submit()`` the submitted transfer descriptor
   (``struct dma_async_tx_descriptor``) belongs to the DMA engine.
   Consequently, the client must consider invalid the pointer to that
   descriptor.
”h]”(h¸)”}”(hŒSubmit the transaction”h]”hŒSubmit the transaction”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Mhj  ubh¸)”}”(hŒ„Once the descriptor has been prepared and the callback information
added, it must be placed on the DMA engine drivers pending queue.”h]”hŒ„Once the descriptor has been prepared and the callback information
added, it must be placed on the DMA engine drivers pending queue.”…””}”(hj!  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Mhj  ubh¸)”}”(hŒ
Interface:”h]”hŒ
Interface:”…””}”(hj/  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h M	hj  ubjç  )”}”(hŒCdma_cookie_t dmaengine_submit(struct dma_async_tx_descriptor *desc)”h]”hŒCdma_cookie_t dmaengine_submit(struct dma_async_tx_descriptor *desc)”…””}”hj=  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h Mhj  ubh¸)”}”(hŒ‡This returns a cookie can be used to check the progress of DMA engine
activity via other DMA engine calls not covered in this document.”h]”hŒ‡This returns a cookie can be used to check the progress of DMA engine
activity via other DMA engine calls not covered in this document.”…””}”(hjL  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Mhj  ubh¸)”}”(hŒ‹dmaengine_submit() will not start the DMA operation, it merely adds
it to the pending queue. For this, see step 5, dma_async_issue_pending.”h]”hŒ‹dmaengine_submit() will not start the DMA operation, it merely adds
it to the pending queue. For this, see step 5, dma_async_issue_pending.”…””}”(hjZ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Mhj  ubhÈ)”}”(hŒÕAfter calling ``dmaengine_submit()`` the submitted transfer descriptor
(``struct dma_async_tx_descriptor``) belongs to the DMA engine.
Consequently, the client must consider invalid the pointer to that
descriptor.”h]”h¸)”}”(hŒÕAfter calling ``dmaengine_submit()`` the submitted transfer descriptor
(``struct dma_async_tx_descriptor``) belongs to the DMA engine.
Consequently, the client must consider invalid the pointer to that
descriptor.”h]”(hŒAfter calling ”…””}”(hjl  hžhhŸNh NubhÖ)”}”(hŒ``dmaengine_submit()``”h]”hŒdmaengine_submit()”…””}”(hjt  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÕhjl  ubhŒ$ the submitted transfer descriptor
(”…””}”(hjl  hžhhŸNh NubhÖ)”}”(hŒ"``struct dma_async_tx_descriptor``”h]”hŒstruct dma_async_tx_descriptor”…””}”(hj†  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÕhjl  ubhŒk) belongs to the DMA engine.
Consequently, the client must consider invalid the pointer to that
descriptor.”…””}”(hjl  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Mhjh  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hÇhj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj  hžhhŸNh Nubj$  )”}”(hX  Issue pending DMA requests and wait for callback notification

The transactions in the pending queue can be activated by calling the
issue_pending API. If channel is idle then the first transaction in
queue is started and subsequent ones queued up.

On completion of each DMA operation, the next in queue is started and
a tasklet triggered. The tasklet will then call the client driver
completion callback routine for notification, if set.

Interface:

.. code-block:: c

   void dma_async_issue_pending(struct dma_chan *chan);
”h]”(h¸)”}”(hŒ=Issue pending DMA requests and wait for callback notification”h]”hŒ=Issue pending DMA requests and wait for callback notification”…””}”(hj®  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Mhjª  ubh¸)”}”(hŒ¹The transactions in the pending queue can be activated by calling the
issue_pending API. If channel is idle then the first transaction in
queue is started and subsequent ones queued up.”h]”hŒ¹The transactions in the pending queue can be activated by calling the
issue_pending API. If channel is idle then the first transaction in
queue is started and subsequent ones queued up.”…””}”(hj¼  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Mhjª  ubh¸)”}”(hŒ½On completion of each DMA operation, the next in queue is started and
a tasklet triggered. The tasklet will then call the client driver
completion callback routine for notification, if set.”h]”hŒ½On completion of each DMA operation, the next in queue is started and
a tasklet triggered. The tasklet will then call the client driver
completion callback routine for notification, if set.”…””}”(hjÊ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h M"hjª  ubh¸)”}”(hŒ
Interface:”h]”hŒ
Interface:”…””}”(hjØ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h M&hjª  ubjç  )”}”(hŒ4void dma_async_issue_pending(struct dma_chan *chan);”h]”hŒ4void dma_async_issue_pending(struct dma_chan *chan);”…””}”hjæ  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h M(hjª  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”j®  j¯  j°  hj±  j²  Œstart”Kuh1j³  hhÿhžhhŸh¶h Mubh¢)”}”(hhh]”(h§)”}”(hŒFurther APIs”h]”hŒFurther APIs”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hj  hžhhŸh¶h M-ubj´  )”}”(hhh]”(j$  )”}”(hX  Terminate APIs

.. code-block:: c

   int dmaengine_terminate_sync(struct dma_chan *chan)
   int dmaengine_terminate_async(struct dma_chan *chan)
   int dmaengine_terminate_all(struct dma_chan *chan) /* DEPRECATED */

This causes all activity for the DMA channel to be stopped, and may
discard data in the DMA FIFO which hasn't been fully transferred.
No callback functions will be called for any incomplete transfers.

Two variants of this function are available.

dmaengine_terminate_async() might not wait until the DMA has been fully
stopped or until any running complete callbacks have finished. But it is
possible to call dmaengine_terminate_async() from atomic context or from
within a complete callback. dmaengine_synchronize() must be called before it
is safe to free the memory accessed by the DMA transfer or free resources
accessed from within the complete callback.

dmaengine_terminate_sync() will wait for the transfer and any running
complete callbacks to finish before it returns. But the function must not be
called from atomic context or from within a complete callback.

dmaengine_terminate_all() is deprecated and should not be used in new code.
”h]”(h¸)”}”(hŒTerminate APIs”h]”hŒTerminate APIs”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h M/hj  ubjç  )”}”(hŒ¬int dmaengine_terminate_sync(struct dma_chan *chan)
int dmaengine_terminate_async(struct dma_chan *chan)
int dmaengine_terminate_all(struct dma_chan *chan) /* DEPRECATED */”h]”hŒ¬int dmaengine_terminate_sync(struct dma_chan *chan)
int dmaengine_terminate_async(struct dma_chan *chan)
int dmaengine_terminate_all(struct dma_chan *chan) /* DEPRECATED */”…””}”hj(  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h M1hj  ubh¸)”}”(hŒÈThis causes all activity for the DMA channel to be stopped, and may
discard data in the DMA FIFO which hasn't been fully transferred.
No callback functions will be called for any incomplete transfers.”h]”hŒÊThis causes all activity for the DMA channel to be stopped, and may
discard data in the DMA FIFO which hasnâ€™t been fully transferred.
No callback functions will be called for any incomplete transfers.”…””}”(hj7  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h M7hj  ubh¸)”}”(hŒ,Two variants of this function are available.”h]”hŒ,Two variants of this function are available.”…””}”(hjE  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h M;hj  ubh¸)”}”(hXœ  dmaengine_terminate_async() might not wait until the DMA has been fully
stopped or until any running complete callbacks have finished. But it is
possible to call dmaengine_terminate_async() from atomic context or from
within a complete callback. dmaengine_synchronize() must be called before it
is safe to free the memory accessed by the DMA transfer or free resources
accessed from within the complete callback.”h]”hXœ  dmaengine_terminate_async() might not wait until the DMA has been fully
stopped or until any running complete callbacks have finished. But it is
possible to call dmaengine_terminate_async() from atomic context or from
within a complete callback. dmaengine_synchronize() must be called before it
is safe to free the memory accessed by the DMA transfer or free resources
accessed from within the complete callback.”…””}”(hjS  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h M=hj  ubh¸)”}”(hŒÑdmaengine_terminate_sync() will wait for the transfer and any running
complete callbacks to finish before it returns. But the function must not be
called from atomic context or from within a complete callback.”h]”hŒÑdmaengine_terminate_sync() will wait for the transfer and any running
complete callbacks to finish before it returns. But the function must not be
called from atomic context or from within a complete callback.”…””}”(hja  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h MDhj  ubh¸)”}”(hŒKdmaengine_terminate_all() is deprecated and should not be used in new code.”h]”hŒKdmaengine_terminate_all() is deprecated and should not be used in new code.”…””}”(hjo  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h MHhj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj  hžhhŸh¶h Nubj$  )”}”(hŒˆPause API

.. code-block:: c

   int dmaengine_pause(struct dma_chan *chan)

This pauses activity on the DMA channel without data loss.
”h]”(h¸)”}”(hŒ	Pause API”h]”hŒ	Pause API”…””}”(hj‡  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h MJhjƒ  ubjç  )”}”(hŒ*int dmaengine_pause(struct dma_chan *chan)”h]”hŒ*int dmaengine_pause(struct dma_chan *chan)”…””}”hj•  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h MLhjƒ  ubh¸)”}”(hŒ:This pauses activity on the DMA channel without data loss.”h]”hŒ:This pauses activity on the DMA channel without data loss.”…””}”(hj¤  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h MPhjƒ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj  hžhhŸh¶h Nubj$  )”}”(hŒ¹Resume API

.. code-block:: c

    int dmaengine_resume(struct dma_chan *chan)

Resume a previously paused DMA channel. It is invalid to resume a
channel which is not currently paused.
”h]”(h¸)”}”(hŒ
Resume API”h]”hŒ
Resume API”…””}”(hj¼  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h MRhj¸  ubjç  )”}”(hŒ+int dmaengine_resume(struct dma_chan *chan)”h]”hŒ+int dmaengine_resume(struct dma_chan *chan)”…””}”hjÊ  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h MThj¸  ubh¸)”}”(hŒhResume a previously paused DMA channel. It is invalid to resume a
channel which is not currently paused.”h]”hŒhResume a previously paused DMA channel. It is invalid to resume a
channel which is not currently paused.”…””}”(hjÙ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h MXhj¸  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj  hžhhŸh¶h Nubj$  )”}”(hXÝ  Check Txn complete

.. code-block:: c

   enum dma_status dma_async_is_tx_complete(struct dma_chan *chan,
             dma_cookie_t cookie, dma_cookie_t *last, dma_cookie_t *used)

This can be used to check the status of the channel. Please see
the documentation in include/linux/dmaengine.h for a more complete
description of this API.

This can be used in conjunction with dma_async_is_complete() and
the cookie returned from dmaengine_submit() to check for
completion of a specific DMA transaction.

.. note::

   Not all DMA engine drivers can return reliable information for
   a running DMA channel. It is recommended that DMA engine users
   pause or stop (via dmaengine_terminate_all()) the channel before
   using this API.
”h]”(h¸)”}”(hŒCheck Txn complete”h]”hŒCheck Txn complete”…””}”(hjñ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h M[hjí  ubjç  )”}”(hŒ†enum dma_status dma_async_is_tx_complete(struct dma_chan *chan,
          dma_cookie_t cookie, dma_cookie_t *last, dma_cookie_t *used)”h]”hŒ†enum dma_status dma_async_is_tx_complete(struct dma_chan *chan,
          dma_cookie_t cookie, dma_cookie_t *last, dma_cookie_t *used)”…””}”hjÿ  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h M]hjí  ubh¸)”}”(hŒ›This can be used to check the status of the channel. Please see
the documentation in include/linux/dmaengine.h for a more complete
description of this API.”h]”hŒ›This can be used to check the status of the channel. Please see
the documentation in include/linux/dmaengine.h for a more complete
description of this API.”…””}”(hj	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Mbhjí  ubh¸)”}”(hŒ£This can be used in conjunction with dma_async_is_complete() and
the cookie returned from dmaengine_submit() to check for
completion of a specific DMA transaction.”h]”hŒ£This can be used in conjunction with dma_async_is_complete() and
the cookie returned from dmaengine_submit() to check for
completion of a specific DMA transaction.”…””}”(hj	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Mfhjí  ubhÈ)”}”(hŒÎNot all DMA engine drivers can return reliable information for
a running DMA channel. It is recommended that DMA engine users
pause or stop (via dmaengine_terminate_all()) the channel before
using this API.”h]”h¸)”}”(hŒÎNot all DMA engine drivers can return reliable information for
a running DMA channel. It is recommended that DMA engine users
pause or stop (via dmaengine_terminate_all()) the channel before
using this API.”h]”hŒÎNot all DMA engine drivers can return reliable information for
a running DMA channel. It is recommended that DMA engine users
pause or stop (via dmaengine_terminate_all()) the channel before
using this API.”…””}”(hj.	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Mlhj*	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hÇhjí  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj  hžhhŸNh Nubj$  )”}”(hX=  Synchronize termination API

.. code-block:: c

   void dmaengine_synchronize(struct dma_chan *chan)

Synchronize the termination of the DMA channel to the current context.

This function should be used after dmaengine_terminate_async() to synchronize
the termination of the DMA channel to the current context. The function will
wait for the transfer and any running complete callbacks to finish before it
returns.

If dmaengine_terminate_async() is used to stop the DMA channel this function
must be called before it is safe to free memory accessed by previously
submitted descriptors or to free any resources accessed within the complete
callback of previously submitted descriptors.

The behavior of this function is undefined if dma_async_issue_pending() has
been called between dmaengine_terminate_async() and this function.”h]”(h¸)”}”(hŒSynchronize termination API”h]”hŒSynchronize termination API”…””}”(hjL	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h MqhjH	  ubjç  )”}”(hŒ1void dmaengine_synchronize(struct dma_chan *chan)”h]”hŒ1void dmaengine_synchronize(struct dma_chan *chan)”…””}”hjZ	  sbah}”(h]”h ]”h"]”h$]”h&]”jö  j÷  jø  ‰jù  jú  jû  }”uh1jæ  hŸh¶h MshjH	  ubh¸)”}”(hŒFSynchronize the termination of the DMA channel to the current context.”h]”hŒFSynchronize the termination of the DMA channel to the current context.”…””}”(hji	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h MwhjH	  ubh¸)”}”(hŒðThis function should be used after dmaengine_terminate_async() to synchronize
the termination of the DMA channel to the current context. The function will
wait for the transfer and any running complete callbacks to finish before it
returns.”h]”hŒðThis function should be used after dmaengine_terminate_async() to synchronize
the termination of the DMA channel to the current context. The function will
wait for the transfer and any running complete callbacks to finish before it
returns.”…””}”(hjw	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h MyhjH	  ubh¸)”}”(hX  If dmaengine_terminate_async() is used to stop the DMA channel this function
must be called before it is safe to free memory accessed by previously
submitted descriptors or to free any resources accessed within the complete
callback of previously submitted descriptors.”h]”hX  If dmaengine_terminate_async() is used to stop the DMA channel this function
must be called before it is safe to free memory accessed by previously
submitted descriptors or to free any resources accessed within the complete
callback of previously submitted descriptors.”…””}”(hj…	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h M~hjH	  ubh¸)”}”(hŒŽThe behavior of this function is undefined if dma_async_issue_pending() has
been called between dmaengine_terminate_async() and this function.”h]”hŒŽThe behavior of this function is undefined if dma_async_issue_pending() has
been called between dmaengine_terminate_async() and this function.”…””}”(hj“	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h MƒhjH	  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j#  hj  hžhhŸh¶h Nubeh}”(h]”h ]”h"]”h$]”h&]”j®  j¯  j°  hj±  j²  uh1j³  hj  hžhhŸh¶h M/ubeh}”(h]”Œfurther-apis”ah ]”h"]”Œfurther apis”ah$]”h&]”uh1h¡hhÿhžhhŸh¶h M-ubeh}”(h]”Œ	dma-usage”ah ]”h"]”Œ	dma usage”ah$]”h&]”uh1h¡hh£hžhhŸh¶h Kubeh}”(h]”Œdma-engine-api-guide”ah ]”h"]”Œdma engine api guide”ah$]”h&]”uh1h¡hhhžhhŸh¶h Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”h¶uh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(h¦NŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ	traceback”ˆŒinput_encoding”Œ	utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”jè	  Œerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œlanguage_code”Œen”Œrecord_dependencies”NŒconfig”NŒ	id_prefix”hŒauto_id_prefix”Œid”Œdump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”h¶Œ_destination”NŒ_config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'Œpep_references”NŒpep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒrfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ	tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œsmart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œdocinfo_xform”KŒsectsubtitle_xform”‰Œimage_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”(jÂ	  j¿	  jº	  j·	  j²	  j¯	  uŒ	nametypes”}”(jÂ	  ‰jº	  ‰j²	  ‰uh}”(j¿	  h£j·	  hÿj¯	  j  uŒfootnote_refs”}”Œcitation_refs”}”Œautofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ	footnotes”]”Œ	citations”]”Œautofootnote_start”KŒsymbol_footnote_start”K Œ
id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”hŒsystem_message”“”)”}”(hhh]”h¸)”}”(hŒ:Enumerated list start value not ordinal-1: "4" (ordinal 4)”h]”hŒ>Enumerated list start value not ordinal-1: â€œ4â€ (ordinal 4)”…””}”(hjO
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  ubah}”(h]”h ]”h"]”h$]”h&]”Œlevel”KŒtype”ŒINFO”Œsource”h¶Œline”Kuh1jJ
  hhÿhžhhŸh¶h MubaŒtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
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