Hi Dmitry,
On Thu, Jan 14, 2021 at 7:24 AM Dmitry Torokhov
<dmitry.torok...@gmail.com> wrote:
>
> A typical USB keyboard usually splits its keys into several reports:
>
> - one for the basic alphanumeric keys, modifier keys, F<n> keys, six pack
> keys and keypad. This report's application is normally listed as
> GenericDesktop.Keyboard
> - a GenericDesktop.SystemControl report for the system control keys, such
> as power and sleep
> - Consumer.ConsumerControl report for multimedia (forward, rewind,
> play/pause, mute, etc) and other extended keys.
> - additional output, vendor specific, and feature reports
>
> Splitting each report into a separate input device is wasteful and even
> hurts userspace as it makes it harder to determine the true capabilities
> (set of available keys) of a keyboard, so let's adjust application
> matching to merge system control and consumer control reports with
> keyboard report, if one has already been processed.
>
> Signed-off-by: Dmitry Torokhov <dmitry.torok...@gmail.com>
> ---
> drivers/hid/hid-input.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> index f797659cb9d9..df45d8d07dc2 100644
> --- a/drivers/hid/hid-input.c
> +++ b/drivers/hid/hid-input.c
> @@ -1851,6 +1851,16 @@ static struct hid_input
> *hidinput_match_application(struct hid_report *report)
> list_for_each_entry(hidinput, &hid->inputs, list) {
> if (hidinput->application == report->application)
> return hidinput;
> +
> + /*
> + * Keep SystemControl and ConsumerControl applications
> together
> + * with the main keyboard, if present.
> + */
> + if ((report->application == HID_GD_SYSTEM_CONTROL ||
> + report->application == HID_CP_CONSUMER_CONTROL) &&
> + hidinput->application == HID_GD_KEYBOARD) {
I am not fundamentally against the patch, but I think that if the
device exposes first a HID_CP_CONSUMER_CONTROL and then a
HID_GD_KEYBOARD we will end up with 2 different input nodes. We likely
need to "convert" HID_GD_SYSTEM_CONTROL and HID_CP_CONSUMER_CONTROL to
HID_GD_KEYBOARD when creating the hidinput.
Cheers,
Benjamin
> + return hidinput;
> + }
> }
>
> return NULL;
> --
> 2.30.0.284.gd98b1dd5eaa7-goog
>
>
> --
> Dmitry
>
