usb_get_descriptor — issues a generic GET_DESCRIPTOR request
|struct usb_device * dev,|
|unsigned char type,|
|unsigned char index,|
|void * buf,|
the device whose descriptor is being retrieved
the descriptor type (USB_DT_*)
the number of the descriptor
where to put the descriptor
how big is “buf”?
Gets a USB descriptor. Convenience functions exist to simplify
getting some types of descriptors. Use
usb_string for USB_DT_STRING.
Device (USB_DT_DEVICE) and configuration descriptors (USB_DT_CONFIG)
are part of the device structure.
In addition to a number of USB-standard descriptors, some
devices also use class-specific or vendor-specific descriptors.
This call is synchronous, and may not be used in an interrupt context.
The number of bytes received on success, or else the status code
returned by the underlying