linux-kernel - Re: [PATCH 0/8] Input: atmel_mxt_ts - output raw touch diagnostic data via V4L

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Date:	Fri, 22 Apr 2016 11:45:17 -0300
From:	Mauro Carvalho Chehab <mchehab@....samsung.com>
To:	Hans Verkuil <hverkuil@...all.nl>
Cc:	Nick Dyer <nick.dyer@...ev.co.uk>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-media@...r.kernel.org,
	Benjamin Tissoires <benjamin.tissoires@...hat.com>,
	Benson Leung <bleung@...omium.org>,
	Alan Bowens <Alan.Bowens@...el.com>,
	Javier Martinez Canillas <javier@....samsung.com>,
	Chris Healy <cphealy@...il.com>,
	Henrik Rydberg <rydberg@...math.org>,
	Andrew Duggan <aduggan@...aptics.com>,
	James Chen <james.chen@....com.tw>,
	Dudley Du <dudl@...ress.com>,
	Andrew de los Reyes <adlr@...omium.org>,
	sheckylin@...omium.org, Peter Hutterer <peter.hutterer@...-t.net>,
	Florian Echtler <floe@...terbrot.org>
Subject: Re: [PATCH 0/8] Input: atmel_mxt_ts - output raw touch diagnostic
 data via V4L

Em Fri, 22 Apr 2016 10:26:37 +0200
Hans Verkuil <hverkuil@...all.nl> escreveu:

> Hi Nick,
> 
> On 04/21/2016 11:31 AM, Nick Dyer wrote:
> > This is a series of patches to add diagnostic data support to the Atmel
> > maXTouch driver. It's a rewrite of the previous implementation which output via
> > debugfs: it now uses a V4L2 device in a similar way to the sur40 driver.
> > 
> > There are significant performance advantages to putting this code into the
> > driver. The algorithm for retrieving the data has been fairly consistent across
> > a range of chips, with the exception of the mXT1386 series (see patch).
> > 
> > We have a utility which can read the data and display it in a useful format:
> > 	https://github.com/ndyer/heatmap/commits/heatmap-v4l
> > 
> > These patches are also available from
> > 	https://github.com/ndyer/linux/commits/diagnostic-v4l
> > 
> > Any feedback appreciated.  
> 
> FYI: we're working on a new buffer type for meta data:
> 
> https://patchwork.linuxtv.org/patch/33938/
> https://patchwork.linuxtv.org/patch/33939/

Nick,

One of the things I missed on your patchset is the content of the
new format you added (V4L2_PIX_FMT_YS16). You should be patching
the V4L2 docbook too, in order to add it there.

That's said, if the output is really an image, I don't think it
should be mapped via the new V4L2_BUF_TYPE_META_CAPTURE. This type of
buffer is meant to be used on non-image metadata, like image statistics
to feed auto whitebalance and other similar AAA algorithms.

It could still make sense to use the new device type (VFL_TYPE_META) for
such drivers, as we don't want applications to identify those devices as
if they are a webcam.

> 
> This would be an excellent fit for you. I expect that this new feature would be
> merged soon (for 4.7 or 4.8 at the latest) since it looks all pretty good to me.
> 
> So let's wait for this to be merged and then you can migrate to the new buffer
> type.
> 
> Regards,
> 
> 	Hans
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-- 
Thanks,
Mauro