Re: 4.1 touchscreen regression on n900 -- pinpointed [was Re: linux-n900 v4.1-rc4]

Pavel Machek
2015-05-29T19:25:11Z

On Fri 2015-05-29 21:08:16, Pavel Machek wrote:
> Hi!
>
> > mh I remember having problems with tsc2005 before. It helped to
> > reset the controller (should actually happen automatically when it
> > hangs, but I'm not sure, that it actually works).
>
> Ok, I did some more testing, and found out rather bogus values in
> evtest:
>
> Input device name: "TSC2005 touchscreen"
> Supported events:
> Event type 0 (EV_SYN)
> Event type 1 (EV_KEY)
> Event code 330 (BTN_TOUCH)
> Event type 3 (EV_ABS)
> Event code 0 (ABS_X)
> Value 2514
> Min 0
> Max 0
> Fuzz 4
>
> Which made me go through the git logs, and these patches looked
> suspicious. After a revert... yes, touchscreen works as well as it
> worked before.
>
> 0a363a380954e10fece7cd9931b66056eeb07d56
> 3eea8b5d68c801fec788b411582b803463834752
>
> (It is impossible to revert just 3eea..)

Hmm, I see:

touchscreen-max-x = <4096>;
touchscreen-max-y = <4096>;
...that's n900 dts.. this should be size-x/size-y... so we have a bug
in dts.

But the 3eea8b5d68c801fec788b411582b803463834752 is buggy, it should
not overwrite ->maximum for axis it has no devicetree data for.

Maybe replacing

+ if (maximum || fuzz)

in 3eea to (maximum && fuzz)... would help, but it is late in the
cycle now, so I'd suggest just reverting 3eea8b.

Thanks,
Pavel

--
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