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

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Message-ID: <2C3C117F-AF7D-4D1D-8644-E788C3BBB1D6@gmail.com>
Date:	Tue, 29 Sep 2015 06:56:36 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Josh Boyer <jwboyer@...oraproject.org>
CC:	"Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>,
	Nick Bowler <nbowler@...conx.ca>,
	Gabor Balla <gaborwho@...il.com>,
	Benjamin Tissoires <btissoir@...hat.com>
Subject: Re: [PATCH 4.1 026/159] Input: synaptics - fix handling of disabling gesture mode

On September 29, 2015 6:44:52 AM PDT, Greg Kroah-Hartman <gregkh@...uxfoundation.org> wrote:
>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@...uxfoundation.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@...uxfoundation.org> wrote:
>> >> > 4.1-stable review patch.  If anyone has any objections, please
>let me know.
>> >> >
>> >> > ------------------
>> >> >
>> >> > From: Dmitry Torokhov <dmitry.torokhov@...il.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@...conx.ca>
>> >> > Suggested-by: Gabor Balla <gaborwho@...il.com>
>> >> > Tested-by: Gabor Balla <gaborwho@...il.com>
>> >> > Tested-by: Nick Bowler <nbowler@...conx.ca>
>> >> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
>> >> > Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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.

Greg,

I'd rather we did not merge this path into stable just yet. I'm not sure if I'll revert it outright or if there will be a fixup, but as is it messes up touchpad behavior for many people :(


Thanks.

-- 
Dmitry
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