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:

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On 03/13/2017 06:15 AM, Benjamin Tissoires wrote:

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On Mar 13 2017 or thereabouts, Benjamin Tissoires wrote:

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On Mar 13 2017 or thereabouts, Thorsten Leemhuis wrote:

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Lo! On 12.03.2017 02:55, Cameron Gutman wrote:

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[…]
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