Hi Mauro, On Apr 07 2017 or thereabouts, Mauro Carvalho Chehab wrote: > As some devices can produce either low-res or high-res > vertical wheel EV_REL events, add a new event to allow > userspace to distinguish between them. > > Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx> > --- > Documentation/input/event-codes.rst | 16 +++++++++++++--- > include/uapi/linux/input-event-codes.h | 1 + > 2 files changed, 14 insertions(+), 3 deletions(-) > > diff --git a/Documentation/input/event-codes.rst b/Documentation/input/event-codes.rst > index 92db50954169..0c8591d39bc6 100644 > --- a/Documentation/input/event-codes.rst > +++ b/Documentation/input/event-codes.rst > @@ -185,10 +185,20 @@ instead of EV_REL codes. > > A few EV_REL codes have special meanings: > > -* REL_WHEEL, REL_HWHEEL: > +* REL_WHEEL: > > - - These codes are used for vertical and horizontal scroll wheels, > - respectively. > + - These codes are used for vertical scroll wheels. > + > + - REL_WHEEL is for normal wheel operational mode, e. g. low-resolution > + (line-based) scroll. > + > + - REL_HIRES_WHEEL should be used when the wheel has two resolutions and it > + is in high-resolution mode, e. g. the same angular movement that would > + produce a single REL_WHEEL will produce multiple REL_HIRES_WHEEL events. > + > +* REL_HWHEEL: > + > + - This code is used for horizontal scroll wheels. > > EV_ABS > ------ > diff --git a/include/uapi/linux/input-event-codes.h b/include/uapi/linux/input-event-codes.h > index 3af60ee69053..23b2d377af59 100644 > --- a/include/uapi/linux/input-event-codes.h > +++ b/include/uapi/linux/input-event-codes.h > @@ -703,6 +703,7 @@ > #define REL_DIAL 0x07 > #define REL_WHEEL 0x08 > #define REL_MISC 0x09 > +#define REL_HIRES_WHEEL 0x0a There is one issue here. The HID input layer has a tendency to map usages to REL_MISC +1, +2, +3, etc... When it doesn't know how to map an usage, the core layer maps it to the next one. I am not aware of devices exposing such REL axes, but I wouldn't be surprised if the issue will not raise at some point. We already had an issue with ABS events where ABS_MISC are conflicting with ABS_MT_SLOTS. Luckily, we have a little empty space between ABS_MISC and ABS_MT_SLOT, which allows userspace to detect such issues. Could you give the define a bigger number (and maybe reserve a couple of REL_MISC-n) to make sure that we do not end up with joysticks exporting REL_HIRES_WHEEL? I'll try the rest of the series on the MX Master today. Cheers, Benjamin > #define REL_MAX 0x0f > #define REL_CNT (REL_MAX+1) > -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
