Re: [PATCH RFC 0/8] Input: atmel_mxt_ts - raw data via debugfs

From: Dmitry Torokhov
Date: Mon Jan 11 2016 - 18:24:21 EST

Hi Nick,

On Thu, Dec 17, 2015 at 05:22:48PM +0000, Nick Dyer wrote:
> On 02/12/15 20:42, Nick Dyer wrote:
> > This is a series of patches to add diagnostic data support to the Atmel
> > maXTouch driver. There's an existing implementation in the open-source mxt-app
> > tool, however there are performance advantages to moving 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).
> >
> > The intention is to open-source a utility which can read/display this data, this
> > should be available very shortly.
> Hi-
> The utility to read this data has now been released, and you can find it at:
> I've recorded a couple of videos of the utility in action on a Pixel 2:
> *
> *

Thank you for sharing the utility and the recording, but it seems that
there is a desire to get access to the heat maps not only for
validation, but also for certain processing purposes, and so I do not
think that we should try to standardize on debugfs as the interface, but
rather look for something that allows better performance.

I wonder if the interface should look similar to the V4L2 capture API
where application opens a character device, uses several ioctls to query
its capabilities/set up capture parameters (i.e reference or deltas),
select()s file descriptor for reading and then uses mmap() to access the
captured heat map.

I've CCed a few people who might be interested in this topic.