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

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Date:   Tue, 14 Mar 2017 09:14:10 +0100
From:   Thorsten Leemhuis <linux@...mhuis.info>
To:     Cameron Gutman <aicommander@...il.com>,
        Andrew Duggan <aduggan@...aptics.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

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?

Ciao, Thorsten