On 04/22/2016 05:07 PM, Nick Dyer wrote: > On 22/04/2016 15:45, Mauro Carvalho Chehab wrote: >> Em Fri, 22 Apr 2016 10:26:37 +0200 >> Hans Verkuil <hverkuil@xxxxxxxxx> escreveu: >>> 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/ >> >> 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. > > OK, will do. I also see that I forgot Kconfig changes for CONFIG_VIDEO_V4L2 > etc. > >> 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. > > The output is raw touch data - i.e. a rectangular grid of nodes each having > an integer value. I think it is an image in some senses, although perhaps > it's a matter of opinion! > > You can see an example of a Atmel MXT capacitive touch device here (using > this patchset): > https://www.youtube.com/watch?v=Uj4T6fUCySw > > There are touch devices which can deliver much higher resolution/framerate. > For example here's the data coming from a SUR40 which is an optical touch > sensor but uses V4L in a similar way: > https://www.youtube.com/watch?v=e-JNqTY_3b0 > >> 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. > > I agree it may be a little confusing if things like Skype start picking up > these devices. Could we #define V4L2_INPUT_TYPE_TOUCH_SENSOR to solve that > problem? > That might be an idea. I have to admit that I didn't look at the patches in detail. It mentioned diagnostics, so I didn't realize that it is a image with a width and height, even though it is not a regular video input. Adding a new input type won't prevent anyone from picking it up, since nobody tests that field :-) On the other hand, it would be a good place to tell the user that it is from a touch sensor. Using the upcoming metadata feature wouldn't work since there is no width and height in the metadata format. I wonder what others think about adding a new type value. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
