[Letux-kernel] [PATCH v9 1/8] drivers:input:tsc2007: add new common binding names, pre-calibration, flipping and rotation

Sebastian Reichel sre at kernel.org
Sat Feb 18 04:22:33 CET 2017


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
$ git grep -l tsc2007

> 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 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
expected. I currently don't have X running on my N900 due some
omapdrm bug, so I can't test this, sorry.

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
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