2.7. ioctls CEC_ADAP_G_PHYS_ADDR and CEC_ADAP_S_PHYS_ADDR¶
CEC_ADAP_G_PHYS_ADDR, CEC_ADAP_S_PHYS_ADDR - Get or set the physical address
This documents the proposed CEC API. This API is not yet finalized and is currently only available as a staging kernel module.
To query the current physical address applications call ioctl CEC_ADAP_G_PHYS_ADDR with a pointer to a __u16 where the driver stores the physical address.
To set a new physical address applications store the physical address in
a __u16 and call ioctl CEC_ADAP_S_PHYS_ADDR with a pointer to
this integer. The ioctl CEC_ADAP_S_PHYS_ADDR is only available if
CEC_CAP_PHYS_ADDR is set (the
ENOTTY error code will be returned
otherwise). The ioctl CEC_ADAP_S_PHYS_ADDR can only be called
by a file descriptor in initiator mode (see ioctls CEC_G_MODE and CEC_S_MODE), if not
EBUSY error code will be returned.
To clear an existing physical address use
The adapter will go to the unconfigured state.
If logical address types have been defined (see ioctl CEC_ADAP_S_LOG_ADDRS), then this ioctl will block until all requested logical addresses have been claimed. If the file descriptor is in non-blocking mode then it will not wait for the logical addresses to be claimed, instead it just returns 0.
A CEC_EVENT_STATE_CHANGE event is sent when the physical address changes.
The physical address is a 16-bit number where each group of 4 bits represent a digit of the physical address a.b.c.d where the most significant 4 bits represent ‘a’. The CEC root device (usually the TV) has address 0.0.0.0. Every device that is hooked up to an input of the TV has address a.0.0.0 (where ‘a’ is ≥ 1), devices hooked up to those in turn have addresses a.b.0.0, etc. So a topology of up to 5 devices deep is supported. The physical address a device shall use is stored in the EDID of the sink.
For example, the EDID for each HDMI input of the TV will have a different physical address of the form a.0.0.0 that the sources will read out and use as their physical address.