Re: [PATCH 2/2] Input: add touchscreen support for TS-4800

From	Damien Riegel <damien.riegel@savoirfairelinux.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/2] Input: add touchscreen support for TS-4800
Date	2015-12-13 22:00 +0100
Message-ID	<qFlUm-4PZ-13@gated-at.bofh.it> (permalink)
References	<qEc6K-5i-9@gated-at.bofh.it> <qEc6L-5i-23@gated-at.bofh.it> <qF6Vj-3FP-1@gated-at.bofh.it>
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Hi Dmitry

On Sat, Dec 12, 2015 at 08:58:58PM -0800, Dmitry Torokhov wrote:
> Hi Damien,
> 
> On Thu, Dec 10, 2015 at 11:11:12AM -0500, Damien Riegel wrote:
> > On this board, the touchscreen, an ads7843, is not handled directly by
> > Linux but by a companion FPGA. This FPGA is memory-mapped and the IP
> > design is very similar to the mk712.
> 
> ...
> 
> > +
> > +	poll_dev = devm_input_allocate_polled_device(&pdev->dev);
> > +	if (!poll_dev)
> > +		return -ENOMEM;
> 
> I wonder how useful touchscreen implemented as polling device is. Isn't
> there an interrupt line for it?
 
There is an interrupt line between the touchscreen and the FGPA, but not
between the FPGA and the SoC. I agree it is a bit peculiar. Hopefully on
more recent boards, they changed their design to handle the touchscreen
directly with Linux.

Thanks,
Damien

> Thanks.
> 
> -- 
> Dmitry
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Re: [PATCH 2/2] Input: add touchscreen support for TS-4800 Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2015-12-13 06:00 +0100
  Re: [PATCH 2/2] Input: add touchscreen support for TS-4800 Damien Riegel <damien.riegel@savoirfairelinux.com> - 2015-12-13 22:00 +0100

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