Re: [PATCH 4.1 026/159] Input: synaptics - fix handling of disabling gesture mode

Greg Kroah-Hartman
2015-09-29T13:45:46Z

On Tue, Sep 29, 2015 at 09:36:15AM -0400, Josh Boyer wrote:
> On Tue, Sep 29, 2015 at 8:53 AM, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> > On Tue, Sep 29, 2015 at 08:27:14AM -0400, Josh Boyer wrote:
> >> On Sat, Sep 26, 2015 at 4:54 PM, Greg Kroah-Hartman
> >> <gregkh@linuxfoundation.org> wrote:
> >> > 4.1-stable review patch. If anyone has any objections, please let me know.
> >> >
> >> > ------------------
> >> >
> >> > From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> >> >
> >> > commit e51e38494a8ecc18650efb0c840600637891de2c upstream.
> >> >
> >> > Bit 2 of the mode byte has dual meaning: it can disable reporting of
> >> > gestures when touchpad works in Relative mode or normal Absolute mode,
> >> > or it can enable so called Extended W-Mode when touchpad uses enhanced
> >> > Absolute mode (W-mode). The extended W-Mode confuses our driver and
> >> > causes missing button presses on some Thinkpads (x250, T450s), so let's
> >> > make sure we do not enable it.
> >> >
> >> > Also, according to the spec W mode "... bit is defined only in Absolute
> >> > mode on pads whose capExtended capability bit is set. In Relative mode and
> >> > in TouchPads without this capability, the bit is reserved and should be
> >> > left at 0.", so let's make sure we respect this requirement as well.
> >> >
> >> > Reported-by: Nick Bowler <nbowler@draconx.ca>
> >> > Suggested-by: Gabor Balla <gaborwho@gmail.com>
> >> > Tested-by: Gabor Balla <gaborwho@gmail.com>
> >> > Tested-by: Nick Bowler <nbowler@draconx.ca>
> >> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> >> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >>
> >> I believe Dmitry is going to revert this commit very shortly. See
> >>
> >> http://www.spinics.net/lists/linux-input/msg41176.html
> >>
> >> You might want to leave this one out of both 4.2.y and 4.1.1y.
> >
> > I prefer to wait for stuff like this to hit Linus's tree to keep in
> > sync, bugs at all at times.
>
> Wait, what? You're going to release a stable kernel with a patch that
> is known to be buggy just to keep it in sync with a buggy upstream
> Linus tree? That doesn't make sense to me. I would maybe understand
> if the upstream solution wasn't "revert this" and instead had a follow
> on patch, but knowing upstream is going to revert and still including
> it is confusing.

We do this all the time, as the patch usually takes a while to get
reverted in Linus's tree, and there doesn't seem to be any "rush" at the
moment to get it reverted, I usually just leave things as-is if for no
other reason than to wake the maintainer up :)

Unless the maintainer asks me not to include it, then I'll reconsider,
otherwise I have to trust that a random person says that the patch will
be reverted some unknown time in the future by some other person, and
that's nothing I can really count on.

Again, keeping the trees in sync, even for bugs, makes things easier
overall.

thanks,

greg k-h