Thread (8 messages) 8 messages, 3 authors, 2013-11-22

Re: [PATCH 1/3] Input: Fixed ABS_MT_TOUCH_MINOR scale factor in BCM5974 multitouch driver

From: Henrik Rydberg <hidden>
Date: 2013-11-21 09:30:43
Also in: lkml

Hi Friedrich,
On wellspring3 devices ABS_MT_TOUCH_MINOR was sometimes reported bigger than
ABS_MT_TOUCH_MAJOR. This is fixed by rescaling ABS_MT_TOUCH_MINOR by a factor of
0.85 instead of 2. Excessive tapping on the trackpad shows this to be the right
value. Circular touches should now lead to values for ABS_MT_TOUCH_MAJOR and
ABS_MT_TOUCH_MINOR that are similar, with ABS_MT_TOUCH_MINOR never greater than
ABS_MT_TOUCH_MAJOR.
---
 drivers/input/mouse/bcm5974.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)
The major/minor scales are following the aspect ratio of the device, and as such
it could happen that minor > major. Most userland drivers do not use the finger
width limits, which are estimates, but only the device axes limit, which are
accurate.

Also, we cannot have floats in the kernel.

I would consider a patch which tries to make the finger widths more accurate,
but all in all, I think this problem is best solved in userland.

Thanks,
Henrik
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