Re: [PATCH v9 1/8] drivers:input:tsc2007: add new common binding names, pre-calibration, flipping and rotation
From: H. Nikolaus Schaller
Date: Sat Feb 18 2017 - 06:33:58 EST
> Am 18.02.2017 um 04:22 schrieb Sebastian Reichel <sre@xxxxxxxxxx>:
> On Fri, Feb 17, 2017 at 12:40:41PM -0800, Dmitry Torokhov wrote:
>>> AFAIK there is no mainline board using the DT except ours (and the upcoming
>>> OMAP5-Pyra), so we shouldn't care too much. If you prefer, you can remove this
>>> compatibility property. We don't need it for our devices.
> $ cd linux.git/arch
> $ git grep -l tsc2004
> $ git grep -l tsc2005
Those are not relevant since tsc2004/5 and tsc2007 are independent drivers and don't
share code. Hence the N900 is not influenced by this patch series.
If it has a similar issue, it should be fixed of course.
> $ git grep -l tsc2007
Sorry, I was a little imprecise here, because I looked for the min/max properties.
Of course, the imx devices use the tsc2007 as well.
Maybe we should edit all these DTS and set the "ti,report-resistance" property
by default. Then, no user should notice a difference.
Is any user/maintainer of these devices following this discussion and can comment?
>> You seem to be treating DT data as something very fluid, which is wrong.
>> You need to treat it as a firmware, unlikely to change once device is
>> shipped. Unlike legacy platform data, the fact that DTS files are not
>> present in mainline does not mean that we can ignore such users and
>> change behavior at will.
>> That said, if driver behavior is out of line from the subsystem
>> expectations, we need to fix it.
>>> That the function name is wrong is a second issue and this double negation might
>>> confuse a litte.
>>> Please test on a real device if the patched driver reports pressure now (unless
>>> ti,report-resistance is specified).
>> I unfortunately can not test this driver as I do not have the hardware.
>> So all my observations are from code and data sheets.
>> That said, what is the values emitted as ABS_PRESSURE when finger is not
>> touching the device, barely touching the device, or pressing firmly?
>> It seems that between TSC2007, TSC2004, TSC2005, and ADS7846, we have
>> confusion as to what is being reported.
> As far as I can see all calculate Rtouch and ADS7846 reports
> (Rmax - Rtouch), which looks sensible.
I don't see where this subtraction from Rmax takes place for the tsc2007:
>> I am adding a few more folks to the CC so we can try and soft this out.
>> Sebastian, Pali, Pavel, any input here?
> I think tsc200x works, since usually userspace is Xorg and I think
> it only cares for x/y coordinates + boolean pressure. Since
> no-pressure is correctly reported as 0, everything works as
No pressure is usually treated as a special case in these drivers,
so reduction to "boolean" in user-space works well by accident and
might still hide a bug.
> I currently don't have X running on my N900 due some
> omapdrm bug, so I can't test this, sorry.
I usually look with evtest if ABS_PRESSURE is monotonic.
> I suggest to put the resistance vs pressure thing in its own patch,
> that also fixes tsc200x-core and merge it to linux-next after the
> merge window.
> -- Sebastian
BR and thanks,
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