Multi-Platform V2.0: Touchpanel buttons not recognized

fs-support_HK · Dec 7th 2012

When pressing buttons on an X application with the touchpanel, the buttons are not correctly recognized. You have to press twice on a button. For example if you start xcalc from the standard root filesystem, you can enter the same digit several times, but if you press another digit, you have to press it twice before it is accepted.

We are already working on a solution.

fs-support_HK · Dec 10th 2012

The following patch solves this problem. The basic patch is just one line, but as we were at it, we also enhanced the description of the generic touch parameters in Kconfig.

Diff

From 16073c5106b2b9ee6ab343512df833ed16684751 Mon Sep 17 00:00:00 2001
Message-Id: <16073c5106b2b9ee6ab343512df833ed16684751.1355144878.git.keller@fs-net.de>
From: Hartmut Keller <keller@fs-net.de>
Date: Mon, 10 Dec 2012 14:03:38 +0100
Subject: [PATCH] Fix bug where buttons are only recognized after second touch
The X server requires two separate touch reports: one for the
position and one for the key-down event. They must not be combined
as one single report as it was done previously.
While we are at it, enhance the descriptions for the generic touch
parameters in Kconfig and fix some typos.
This commit resolves bugtracker issue #1489.
---
drivers/input/touchscreen/Kconfig | 55 +++++++++++++++++--------------
drivers/input/touchscreen/s3c2410_ts.c | 1 +
2 files changed, 31 insertions(+), 25 deletions(-)
diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 9992f23..260674e 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -233,13 +233,14 @@ config TOUCHSCREEN_S3C_SETUP_CYCLES
depends on TOUCHSCREEN_S3C2410
default 10000
help
- Set the time to wait after changing the touch configuration
- before fetching the first sample. The value is given in
- PCLK cycles. For example if PCLK is 66MHz, a value of 10000
- will result in about 150us setup delay. If this value is
+ Set the time to wait during measurement after changing the touch
+ configuration but before fetching the first sample. The value is
+ given in PCLK cycles. For example if PCLK is 66MHz, a value of
+ 10000 will result in about 150us setup delay. If this value is
chosen too small, the charging process is not fully completed
- when the measurement takes place, resulting in innacurate
- positions.
+ when the measurement takes place, resulting in inaccurate
+ positions. This time is only required before the first sample
+ of a type (x, y, p).
config TOUCHSCREEN_S3C_SAMPLES
int "Samples per value"
@@ -247,15 +248,15 @@ config TOUCHSCREEN_S3C_SAMPLES
default 64
help
Set the number of samples s to take for each of the values x, y
- and p (pressure). The setup delay is only required before the
- first sample of each of these values. The higher the value,
- the more accurate is the position measurement. The result is
- determined by skipping the smallest s/4 and the highest s/4
- samples (to reduce impulse noise) and by building the mean value
- over remaining samples (to reduce Gaussian noise). For example
- if s is set to 20, the five smallest and five highest samples are
- discarded and the final value is computed as the mean value over
- the remaining ten samples.
+ and p (pressure). The higher the value, the more accurate is the
+ position measurement. The result is determined by skipping the
+ smallest s/4 and the highest s/4 samples (to reduce impulse noise)
+ and by building the mean value over the remaining samples (to
+ reduce Gaussian noise).
+
+ For example if s is set to 20, the five smallest and five highest
+ samples are discarded and the final value is computed as the mean
+ value over the remaining ten samples.
config TOUCHSCREEN_S3C_DEBOUNCE
int "Debounce count"
@@ -277,25 +278,29 @@ config TOUCHSCREEN_S3C_INTERVAL
while the screen is touched.
config TOUCHSCREEN_S3C_THRESHOLD_P
- int "Pressure threshold (in %)"
+ int "Pressure threshold (as touch resistor limit, in %)"
depends on TOUCHSCREEN_S3C2410
default 700
help
If the down-force (pressure) on the touch screen is very low,
the measurement of the position gets inaccurate. Therefore the
- driver evaluates the down-force by measuring the touch resistance
- between x plane and y plane of the touch panel. The result is not
- an absolute value, but a percentage in relation to the resistor
- value Rx of the x plane. The higher the resistor value, the lower
- the down-force.
+ driver evaluates the down-force by measuring the touch resistor
+ between x plane and y plane of the touch panel. The higher the
+ touch resistor value, the lower the down-force.
+
+ The result for this touch resistor is not computed as an absolute
+ value, but as a percentage in relation to the resistor value Rx
+ of the x plane. By using only such a relative value, we also
+ don't need to know the absolute value of Rx, too.
- All measurements with a resitor value higher than this threshold
+ All measurements with a resistor value higher than this threshold
value are discarded. For example if this value is set to 500, all
- measurements where the touch resistance exceeds 5x Rx are ignored.
+ measurements where the touch resistor exceeds 5 times the value
+ of Rx are ignored.
If you have to press rather hard on the screen to get a reaction,
- use a higher here. If the measurement is very inaccurate, use a
- lower value here.
+ use a higher value here. If the measurement is very inaccurate,
+ use a lower value here.
config TOUCHSCREEN_S3C_JITTER_P
int "Jitter tolerance for pressure"
diff --git a/drivers/input/touchscreen/s3c2410_ts.c b/drivers/input/touchscreen/s3c2410_ts.c
index ffd43c9..32db46f 100644
--- a/drivers/input/touchscreen/s3c2410_ts.c
+++ b/drivers/input/touchscreen/s3c2410_ts.c
@@ -649,6 +649,7 @@ static void s3c24xx_ts_select(struct s3c_adc_client *client, unsigned select)
ts.y = sa_get_average(&sa_finaly, 0);
input_report_abs(ts.input, ABS_X, ts.x);
input_report_abs(ts.input, ABS_Y, ts.y);
+ input_sync(ts.input);
input_report_key(ts.input, BTN_TOUCH, 1);
input_sync(ts.input);
dev_dbg(ts.dev, "Accept X=%d Y=%d P=%d\n",
--
1.7.4.4

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This patch is also attached to this post for download. To apply it simply go into the top directory of your Linux source tree and say

Code

patch -p1 < Fix-bug-where-buttons-are-only-recognized-after-second-touch.patch

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