Dear Marek,
On 07/10/2013 01:49 PM, Marek Vasut wrote:
Hi Hector,
Hello,
On 07/05/2013 03:10 PM, Marek Vasut wrote:
Dear Hector Palacios,
Dear Marek,
On 07/05/2013 01:37 PM, Marek Vasut wrote:
Dear Hector Palacios,
The LRADC virtual channels have an 18 bit field to store the sum of up
to 2^5 accumulated samples. The read_raw function however only
operates over a single sample (12 bit resolution).
In order to use this field for scaling operations, we need it to be
the exact resolution value of the LRADC.
How would this work once the accumulation is supported?
As I see it, when you read a channel the driver should give you the
12-bit value either of one single sample or of N samples.
The hardware will always give you 18 bit value, let's call it A of N
accumulated samples, each 12 bit long. N is in range of 1 to 32 .
The driver currently supports N = 1.
Do I understand it correctly that if we want to support N > 1, we have to
do the division of A / N in the driver and therefore we will again
report only a 12-bit value to the userland ?
If so,
Acked-by: Marek Vasut <marex@xxxxxxx>
Coming back to this patch, I just noticed that it is not enough to just
change the realbits from 18 to 12. When using this driver as touchscreen
for Yocto's SATO graphic rootfs I noticed that the driver is using
LRADC_CH_VALUE_MASK for reporting the coordinates.
input_set_abs_params(input, ABS_X, 0, LRADC_CH_VALUE_MASK, 0, 0);
input_set_abs_params(input, ABS_Y, 0, LRADC_CH_VALUE_MASK, 0, 0);
input_set_abs_params(input, ABS_PRESSURE, 0, LRADC_CH_VALUE_MASK, 0, 0);
which is defined as an 18bit mask:
#define LRADC_CH_VALUE_MASK 0x3ffff
The result is that the touch calibration range in Xorg is expecting values
between 0 and 262143 (0x3ffff), which causes trouble (at least I had
problems to calibrate it).
What kind of trouble does it cause?
Sorry, I should have said.
First of all, I'm using a resistive touch that needs calibration.
There something I definitely don't understand about calibrating the touch in Sato.
Initially I don't have any file /etc/pointercal.xinput. When Sato launches the touch
is not calibrated so I run the xinput_calibrator. When I run this, the console displays:
Calibrating EVDEV driver for "mxs-lradc" id=6
current calibration values (from XInput): min_x=0, max_x=262143 and min_y=0,
max_y=262143
Notice the max_x and max_y are showing 0x3ffff which is the value sent by the driver.
This calibration program shows a target at each corner. At this point, it will only
accept me clicking on the first target (upper left corner). When I click the second it
doesn't get it. It eventually gets it if I click several times somewhere else in the
screen, but yet it won't get the third target (lower left corner), no matter where I
press. So I can't calibrate the touch. I believe the reason might be the calibration
tool is expecting much higher values (around the max value) and maybe discarding
values that are too close (in relation to the range) to the min coordinate (it's just
my guess).
After doing the above patch, when launching the vcalibration tool, I get this on the
console:
Calibrating EVDEV driver for "mxs-lradc" id=6
current calibration values (from XInput): min_x=0, max_x=4095 and min_y=0,
max_y=4095
and the application lets me click on every target. The application showed the
following output:
Doing dynamic recalibration:
Swapping X and Y axis...
Setting calibration data: 1405, 1367, 3693, 3733
--> Making the calibration permanent <--
copy the snippet below into '/etc/X11/xorg.conf.d/99-calibration.conf'
Section "InputClass"
Identifier "calibration"
MatchProduct "mxs-lradc"
Option "Calibration" "1405 1367 3693 3733"
Option "SwapAxes" "1"
EndSection
I created the file /etc/X11/xorg.conf.d/99-calibration.conf and wrote that
information, but the touch still didn't work correctly. :o(
I manually removed the "Calibration" line from this file and launched the calibration
tool again. This time I was given the following data:
Section "InputClass"
Identifier "calibration"
MatchProduct "mxs-lradc"
Option "Calibration" "4207 320 4063 326"
Option "SwapAxes" "1"
EndSection
and finally the touch works correctly calibrated.
So, ok, maybe the driver is not responsible for all these problems, but reporting a
max value of 0x3ffff seems definitely incorrect, and it was preventing me from
completing the calibration.
[...]
Notice that I leave the existing LRADC_CH_VALUE_MASK 18bit mask in the rest
of the driver, to support accumulated samples.
Curiously, ts_lib works fine without this (maybe the calibration fixes
this?), but nevertheless the information passed by the driver is
incorrect, I guess. Is anybody out there working with the touch? Under
which graphic system?
Both QtE and Sato work for me, that's why I'm curious about your issues.
ts_lib application also worked for me without the patch, but I thought maybe the
ts_calibrate was doing his job regardless the ranges reported by the driver and the
Sato worked differently.
Are you also using a resistive touch? How did you do the calibration?
Best regards,
--
Hector Palacios
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