On Wed, 2020-02-12 at 14:50 +0100, Jiri Kosina wrote:
> On Wed, 15 Jan 2020, Filipe Laíns wrote:
>
> > The Logitech G Powerplay has a lightspeed receiver with a static HID++
> > device with ID 7 attached to it to. It is used to configure the led on
> > the mat. For this reason I increased the max number of devices.
> >
> > Signed-off-by: Filipe Laíns <lains@xxxxxxxxxxxxx>
> > ---
> > drivers/hid/hid-logitech-dj.c | 9 +++++++--
> > 1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
> > index bb50d6e7745b..79294b873057 100644
> > --- a/drivers/hid/hid-logitech-dj.c
> > +++ b/drivers/hid/hid-logitech-dj.c
> > @@ -16,11 +16,11 @@
> > #include <asm/unaligned.h>
> > #include "hid-ids.h"
> >
> > -#define DJ_MAX_PAIRED_DEVICES 6
> > +#define DJ_MAX_PAIRED_DEVICES 7
> > #define DJ_MAX_NUMBER_NOTIFS 8
> > #define DJ_RECEIVER_INDEX 0
> > #define DJ_DEVICE_INDEX_MIN 1
> > -#define DJ_DEVICE_INDEX_MAX 6
> > +#define DJ_DEVICE_INDEX_MAX 7
> >
> > #define DJREPORT_SHORT_LENGTH 15
> > #define DJREPORT_LONG_LENGTH 32
> > @@ -980,6 +980,11 @@ static void logi_hidpp_recv_queue_notif(struct hid_device *hdev,
> > break;
> > }
> >
> > + /* custom receiver device (eg. powerplay) */
> > + if (hidpp_report->device_index == 7) {
> > + workitem.reports_supported |= HIDPP;
> > + }
> > +
>
> I guess we can't do anything else than to trust Logitech that they will
> not assign conflicting device_index ID in the future to something that
> will not be HID++, right?
>
> Or is this properly documented somewhere?
>
> Thanks,
CCing Nestor
Yes, we need to trust Logitech on this. There's isn't anything
documented regarding this AFAIK.
Even if Logitech released a device with index 7 that didn't support
HID++, it wouldn't be that big of an issue. We would just end up with a
hidraw node which would export a vendor page report descriptor but the
device wouldn't actually reply to anything.
Regards,
Filipe Laíns
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