[Letux-kernel] [Gta04-owner] evtest /dev/input/accel

H. Nikolaus Schaller hns at goldelico.com
Tue Apr 17 15:00:24 CEST 2018


> Am 17.04.2018 um 14:08 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> Hi,
> 
> For the "stuttering" problem of QtMaze I suspect that the graphics backend
> of Qt waits for vertical retrace to guard the frame rate. This ioctl might
> different from new kernels with kernel 3.7... AFAIR the whole omap3 display
> system has been replaced since that times.
> 
> Maybe, next I should try if I can boot our latest QtMoko2 with a 3.7 kernel :)
> Just for comparison.

Was a little tricky:

1. I installed: http://download.goldelico.com/letux-kernel/3.7-neil-plus-plus/

2. I had to remove all .dtb because our u-boot then tries to start the kernel
   in DTB mode

3. the kernel insisted on repairing the µSD and UBIFS...

4. touchscreen was not working (although evtest /dev/input/touchscreen succeeded)
but I could do

	. /opt/qtmoko/qpe.env
	/opt/qtmoko/bin/qtmaze

QtMaze was noticeably faster...

What I then tried was evtest /dev/input/accel

a) with 3.7 kernel

Testing ... (interrupt to exit)
Event: time 946685215.589734, type 3 (EV_ABS), code 0 (ABS_X), value -18
Event: time 946685215.589734, type 3 (EV_ABS), code 2 (ABS_Z), value 254
Event: time 946685215.589734, -------------- SYN_REPORT ------------
Event: time 946685215.605297, type 3 (EV_ABS), code 0 (ABS_X), value -21
Event: time 946685215.605297, type 3 (EV_ABS), code 1 (ABS_Y), value 4
Event: time 946685215.605297, type 3 (EV_ABS), code 2 (ABS_Z), value 267
Event: time 946685215.605297, -------------- SYN_REPORT ------------
Event: time 946685215.620922, type 3 (EV_ABS), code 0 (ABS_X), value -24
Event: time 946685215.620922, type 3 (EV_ABS), code 1 (ABS_Y), value 6
Event: time 946685215.620922, type 3 (EV_ABS), code 2 (ABS_Z), value 266
Event: time 946685215.620922, -------------- SYN_REPORT ------------
Event: time 946685215.636638, type 3 (EV_ABS), code 0 (ABS_X), value -23
Event: time 946685215.636638, type 3 (EV_ABS), code 1 (ABS_Y), value 13
Event: time 946685215.636638, type 3 (EV_ABS), code 2 (ABS_Z), value 258
Event: time 946685215.636638, -------------- SYN_REPORT ------------
Event: time 946685215.652141, type 3 (EV_ABS), code 0 (ABS_X), value -18
Event: time 946685215.652141, type 3 (EV_ABS), code 1 (ABS_Y), value 5
Event: time 946685215.652141, type 3 (EV_ABS), code 2 (ABS_Z), value 259
Event: time 946685215.652141, -------------- SYN_REPORT ------------
Event: time 946685215.668040, type 3 (EV_ABS), code 0 (ABS_X), value -19
Event: time 946685215.668040, type 3 (EV_ABS), code 1 (ABS_Y), value 6
Event: time 946685215.668040, type 3 (EV_ABS), code 2 (ABS_Z), value 269
Event: time 946685215.668040, -------------- SYN_REPORT ------------
Event: time 946685215.683604, type 3 (EV_ABS), code 0 (ABS_X), value -26
Event: time 946685215.683604, type 3 (EV_ABS), code 1 (ABS_Y), value 10
Event: time 946685215.683604, type 3 (EV_ABS), code 2 (ABS_Z), value 257
Event: time 946685215.683604, -------------- SYN_REPORT ------------
Event: time 946685215.699015, type 3 (EV_ABS), code 0 (ABS_X), value -20
Event: time 946685215.699015, type 3 (EV_ABS), code 1 (ABS_Y), value 8
Event: time 946685215.699015, -------------- SYN_REPORT ------------

b) back on 4.16

Testing ... (interrupt to exit)
Event: time 946684849.213714, type 3 (EV_ABS), code 0 (ABS_X), value 32
Event: time 946684849.213714, type 3 (EV_ABS), code 2 (ABS_Z), value -249
Event: time 946684849.213714, -------------- SYN_REPORT ------------
Event: time 946684849.428557, type 3 (EV_ABS), code 2 (ABS_Z), value -250
Event: time 946684849.428557, -------------- SYN_REPORT ------------
Event: time 946684849.537780, type 3 (EV_ABS), code 0 (ABS_X), value 33
Event: time 946684849.537780, -------------- SYN_REPORT ------------
Event: time 946684849.647735, type 3 (EV_ABS), code 0 (ABS_X), value 32
Event: time 946684849.647735, type 3 (EV_ABS), code 2 (ABS_Z), value -249
Event: time 946684849.647735, -------------- SYN_REPORT ------------
Event: time 946684849.757964, type 3 (EV_ABS), code 0 (ABS_X), value 33
Event: time 946684849.757964, type 3 (EV_ABS), code 2 (ABS_Z), value -250
Event: time 946684849.757964, -------------- SYN_REPORT ------------
Event: time 946684849.868285, type 3 (EV_ABS), code 0 (ABS_X), value 32
Event: time 946684849.868285, type 3 (EV_ABS), code 2 (ABS_Z), value -249
Event: time 946684849.868285, -------------- SYN_REPORT ------------
Event: time 946684849.978332, type 3 (EV_ABS), code 2 (ABS_Z), value -250
Event: time 946684849.978332, -------------- SYN_REPORT ------------
Event: time 946684850.198302, type 3 (EV_ABS), code 0 (ABS_X), value 33
Event: time 946684850.198302, -------------- SYN_REPORT ------------

So the average time between input events is ca. 15 ms on 3.7 kernel
while it is 200 ms on the 4.16!

This gives of course a "delayed" experience...

Maybe, our iio sensor is not set up for faster reporting???

Well,

	echo 300 >/sys/module/bma180/drivers/i2c:bma180/1-0041/iio:device1/in_accel_filter_low_pass_3db_frequency

makes events appear a little quicker ... Ca. 100 ms but not 15 ms.

In other words: the old kernel is simply sampling much faster.

BR,
Nikolaus



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