Re: [PATCH 0/9 v2] Synaptics image sensor support

Chase Douglas
2011-07-23T01:13:21Z

On 07/20/2011 06:38 AM, djkurtz@chromium.org wrote:
> From: Daniel Kurtz <djkurtz@chromium.org>
> Patches 4-7 add up to 3 finger support for image sensor touchpads.
> Image sensors do not suffer from the finger tracking issues that plagued
> the earlier "profile sensors", and which required the invention of "semi-mt"
> (Semi-mt reports a bounding box around two fingers instead of the fingers
> themselves). Instead, the image sensors report the actual positions of two
> fingers using the same "Advanced Gesture Mode". This driver uses two MT-B slots
> to report these two fingers to userspace. In addition, it will also report
> the total number of fingers using BTN_TOOL_*TAP EV_KEY events.
> Userspace drivers should be aware that the number of fingers reported via
> BTN_TOOL_*TAP can be greater than the total number MT-B slots with non-negative
> track_ids. Upon opening the device node, userspace should query the maximum
> values supported ABS_MT_SLOT, and note the number of supported BTN_TOOL_*TAP
> events.

I would still rather see a new property bit for devices that track and
report different numbers of touches. I think it is worthwhile to be
explicit here rather than leave it up to voodoo magic in userpace drivers.

This and the touch count transition issue I brought up in a reply to
patch 7 are my only concerns with this part of the patchset.

BTW, I found the commit messages and the code to be very comprehensible.
Good job on cleaning them up!

-- Chase