Re: [GIT] HID for 3.12 merge window

[Dmitry Torokhov]

On Sat, Sep 07, 2013 at 12:51:27AM +0200, David Herrmann wrote:
> Hi
> 
> On Fri, Sep 6, 2013 at 11:59 PM, Markus Trippelsdorf
> <markus@xxxxxxxxxxxxxxx> wrote:
> > On 2013.09.06 at 23:50 +0200, David Herrmann wrote:
> >> Hi
> >>
> >> On Fri, Sep 6, 2013 at 10:20 PM, Markus Trippelsdorf
> >> <markus@xxxxxxxxxxxxxxx> wrote:
> >> > On 2013.09.06 at 14:00 +0200, Jiri Kosina wrote:
> >> >>
> >> >> David Herrmann (12):
> >> > ...
> >> >>       HID: wiimote: add support for Guitar-Hero drums
> >> >
> >> >  commit 61e00655e9cb82e034eb72b95a51072e718d14a7
> >> >  Author: David Herrmann <dh.herrmann@xxxxxxxxx>
> >> >  Date:   Mon Aug 26 19:14:46 2013 +0200
> >> >
> >> >      Input: introduce BTN/ABS bits for drums and guitars
> >> >
> >> > The commit above breaks my Logitech mouse. The mouse cursor just sits in
> >> > the middle of the screen and doesn't react to movements. dmesg is
> >> > normal, but Xorg.0.log says:
> >>
> >> Ok, the issue is the kernel assumes ABS_MAX to be a power-of-2 minus 1
> >> (used as mask). That wasn't really obvious to me. Attached is a patch
> >> which should fix that. Could you apply it on top of linus/master and
> >> give it a try?
> >
> > Your patch fixes the issue. Thanks.
> 
> Thanks a lot for reporting+testing!
> 
> I am still not sure how to solve the EVIOCSABS thingy. Problem is,
> it's defined as:
>   #define EVIOCSABS(_abs) ...0xc0 + (_abs)...
> But if (_abs > 0x3f) this will be bigger than 0xff. Unfortunately, the
> upper part of the ioctl is defined as 'E' which is 0x45 in hex and
> thus sets the LSB. That means we cannot extend the _IOC_TYPE field to
> the upper region (which would cause endian-issues, anyway). I guess
> we're screwed here and need to revert that...
> 
> Dmitry, any comment on this? Or am I missing something?

We have gaps below ABS_MT constants, I think for 3.12 you could move
your whammy there and revert ABS_MAX change, but we need to plan for
expanding it in the future.

Thanks.

-- 
Dmitry
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