tree cf265121361d49572f7941734bffaa3b4611e386
parent 6a0eaf5123e0e1223252b88cd5775f74105e27bd
author Dean Camera <dean@fourwalledcubicle.com> 1606343997 +1100
committer Jiri Kosina <jkosina@suse.cz> 1606488511 +0100

HID: hidraw: Add additional hidraw input/output report ioctls.

Currently the hidraw module can only read and write feature HID reports on
demand, via dedicated ioctls. Input reports are read from the device through
the read() interface, while output reports are written through the write
interface().

This is insufficient; it is desirable in many situations to be able to read and
write input and output reports through the control interface to cover
additional scenarios:

  - Reading an input report by its report ID, to get initial state
  - Writing an input report, to set initial input state in the device
  - Reading an output report by its report ID, to obtain current state
  - Writing an output report by its report ID, out of band

This patch adds these missing ioctl requests to read and write the remaining
HID report types. Note that not all HID backends will neccesarily support this
(e.g. while the USB link layer supports setting Input reports, others may not).

Also included are documentation and example updates. The current hidraw
documentation states that feature reports read from the device does *not*
include the report ID, however this is not the case and the returned report
will have its report ID prepended by conforming HID devices, as the report data
sent from the device over the control endpoint must be indentical in format to
those sent over the regular transport.

Signed-off-by: Dean Camera <dean@fourwalledcubicle.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>