linux-kernel - Re: Synaptics RMI4 touchpad regression in 4.11-rc1

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Date:   Tue, 14 Mar 2017 18:20:03 -0700
From:   Andrew Duggan <aduggan@...aptics.com>
To:     Thorsten Leemhuis <linux@...mhuis.info>,
        Cameron Gutman <aicommander@...il.com>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Jiri Kosina <jikos@...nel.org>
CC:     <nick@...anahar.org>, <cheiny@...aptics.com>,
        <linux-input@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: Synaptics RMI4 touchpad regression in 4.11-rc1

On 03/14/2017 01:14 AM, Thorsten Leemhuis wrote:
> Lo! On 14.03.2017 06:10, Cameron Gutman wrote:
>> On 03/13/2017 06:35 PM, Andrew Duggan wrote:
>>> On 03/13/2017 06:15 AM, Benjamin Tissoires wrote:
>>>> On Mar 13 2017 or thereabouts, Benjamin Tissoires wrote:
>>>>> On Mar 13 2017 or thereabouts, Thorsten Leemhuis wrote:
>>>>>> Lo! On 12.03.2017 02:55, Cameron Gutman wrote:
>>>>>>> […]
>>>>>>> Compared to hid-multitouch, the RMI stack seems to have completely broken
>>>>>>> palm rejection and introduced some random jumpiness during fine pointing
>>>>>>> motions. […]
>>>>>> Just to confirm: I noticed "jumpiness during fine pointing motions" as
>>>>>> well since switching to 4.11-rc.
>>>> One of my test systems is a XPS 13 9343 and I have not really
>>>> seen any jumpiness. But, based on the data I am seeing that if I
>>>> lift my finger and place it again in a short period of time the
>>>> first event or so will be at the location of the previous
>>>> contact. Then it will switch over to the current location. When
>>>> switching over to hid-multitouch I was unable to reproduce this
>>>> behavior. This definitely could be the source of the jumps.
>> The jumpiness definitely happens without lifting my finger, but I'm willing
>> to test any patch you think would improve the situation. Moving one finger
>> slowly in a figure-8 across my touchpad shows the issue clearly for me. The
>> small variations in speed of my finger due to the friction on the trackpad
>> get magnified to relatively large jumpy pointer movements on screen. It
>> seems much more noticeable in diagonal movements than completely vertical
>> or horizontal movements.
> @Andrew: Is there anything we can do to help track this down? A
> evemu-record of some movements or something like that? Or do we need to
> bring Peter into the loop in case it has something to do with libinput?

Yes, collecting some evemu-record logs of the jumps would be useful. 
Only after installing Fedora 25 was I able to see jumps while moving 
diagonally. I'm interested in seeing what others record and if it is the 
same as what I saw. The log of the jump did show the jump on Fedora 25. 
But, I did not see the jump with Ubuntu 16.10 with libinput 1.4.3.

Andrew

> Ciao, Thorsten