[PATCH 1/3] Replace "variance" filter with "group" filter
Nelson Castillo
nelsoneci at gmail.com
Mon Dec 8 04:49:31 CET 2008
This filter is useful to reject samples that are not reliable. We consider
that a sample is not reliable if it deviates form the Majority.
This filter performs better than the variance filter thus we can replace it.
I will remove the skip filter later.
I haven't seen a bad click in a while. Somebody wake me up.
Signed-off-by: Nelson Castillo <nelsoneci at gmail.com>
---
0 files changed, 0 insertions(+), 0 deletions(-)
diff --git a/arch/arm/configs/gta02-moredrivers-defconfig b/arch/arm/configs/gta02-moredrivers-defconfig
index eb7d6b7..fbaf760 100644
--- a/arch/arm/configs/gta02-moredrivers-defconfig
+++ b/arch/arm/configs/gta02-moredrivers-defconfig
@@ -980,9 +980,9 @@ CONFIG_INPUT_MOUSE=y
# CONFIG_INPUT_TABLET is not set
CONFIG_INPUT_TOUCHSCREEN=y
CONFIG_TOUCHSCREEN_FILTER=y
+CONFIG_TOUCHSCREEN_FILTER_GROUP=y
CONFIG_TOUCHSCREEN_FILTER_MEDIAN=y
CONFIG_TOUCHSCREEN_FILTER_MEAN=y
-CONFIG_TOUCHSCREEN_FILTER_VARIANCE=y
# CONFIG_TOUCHSCREEN_ADS7846 is not set
# CONFIG_TOUCHSCREEN_FUJITSU is not set
CONFIG_TOUCHSCREEN_S3C2410=y
diff --git a/arch/arm/mach-s3c2440/mach-gta02.c b/arch/arm/mach-s3c2440/mach-gta02.c
index 41ba0c8..e90f82b 100644
--- a/arch/arm/mach-s3c2440/mach-gta02.c
+++ b/arch/arm/mach-s3c2440/mach-gta02.c
@@ -105,7 +105,7 @@
#include <linux/ts_filter_mean.h>
#include <linux/ts_filter_median.h>
-#include <linux/ts_filter_variance.h>
+#include <linux/ts_filter_group.h>
/* arbitrates which sensor IRQ owns the shared SPI bus */
static spinlock_t motion_irq_lock;
@@ -1019,35 +1019,34 @@ static struct s3c2410_udc_mach_info gta02_udc_cfg = {
/* touchscreen configuration */
-static struct ts_filter_variance_configuration gta02_ts_variance_config = {
- .extent = 20,
- .window = 5,
- .threshold = 10, /* variance = 10, std = 3.1623 */
- .attempts = 5, /* try 5 times before giving up */
+static struct ts_filter_group_configuration gta02_ts_group_config = {
+ .extent = 12,
+ .close_enough = 10,
+ .threshold = 6, /* at least half of the points in a group */
+ .attempts = 10,
};
static struct ts_filter_median_configuration gta02_ts_median_config = {
- .extent = 31,
- .decimation_below = 5,
+ .extent = 20,
+ .decimation_below = 3,
.decimation_threshold = 8 * 3,
- .decimation_above = 10,
+ .decimation_above = 4,
};
static struct ts_filter_mean_configuration gta02_ts_mean_config = {
- .bits_filter_length = 3,
- .averaging_threshold = 6 * 3,
+ .bits_filter_length = 2, /* 4 points */
};
static struct s3c2410_ts_mach_info gta02_ts_cfg = {
.delay = 10000,
.presc = 0xff, /* slow as we can go */
.filter_sequence = {
- [0] = &ts_filter_variance_api,
+ [0] = &ts_filter_group_api,
[1] = &ts_filter_median_api,
[2] = &ts_filter_mean_api,
},
.filter_config = {
- [0] = >a02_ts_variance_config,
+ [0] = >a02_ts_group_config,
[1] = >a02_ts_median_config,
[2] = >a02_ts_mean_config,
},
diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 98566fd..a0f8599 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -21,13 +21,13 @@ menuconfig TOUCHSCREEN_FILTER
if TOUCHSCREEN_FILTER
-config TOUCHSCREEN_FILTER_VARIANCE
- bool "Variance Touchscreen Filter"
+config TOUCHSCREEN_FILTER_GROUP
+ bool "Group Touchscreen Filter"
depends on INPUT_TOUCHSCREEN && TOUCHSCREEN_FILTER
default Y
help
- Say Y here if you want to use the Variance touchscreen filter, it
- helps discarding a click if we get too much noise.
+ Say Y here if you want to use the Group touchscreen filter, it
+ avoids using atypical samples.
config TOUCHSCREEN_FILTER_MEDIAN
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index ee6bd28..9a6162c 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -33,6 +33,6 @@ wm97xx-ts-$(CONFIG_TOUCHSCREEN_WM9713) += wm9713.o
obj-$(CONFIG_TOUCHSCREEN_WM97XX_MAINSTONE) += mainstone-wm97xx.o
obj-$(CONFIG_TOUCHSCREEN_S3C2410) += s3c2410_ts.o
obj-$(CONFIG_TOUCHSCREEN_FILTER) += ts_filter.o
-obj-$(CONFIG_TOUCHSCREEN_FILTER_VARIANCE) += ts_filter_variance.o
+obj-$(CONFIG_TOUCHSCREEN_FILTER_GROUP) += ts_filter_group.o
obj-$(CONFIG_TOUCHSCREEN_FILTER_MEDIAN) += ts_filter_median.o
obj-$(CONFIG_TOUCHSCREEN_FILTER_MEAN) += ts_filter_mean.o
diff --git a/drivers/input/touchscreen/ts_filter_group.c b/drivers/input/touchscreen/ts_filter_group.c
new file mode 100644
index 0000000..250613f
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_group.c
@@ -0,0 +1,217 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (C) 2008 by Openmoko, Inc.
+ * Author: Nelson Castillo <arhuaco at freaks-unidos.net>
+ * All rights reserved.
+ *
+ * This filter is useful to reject samples that are not reliable. We consider
+ * that a sample is not reliable if it deviates form the Majority.
+ *
+ * 1) We collect S samples.
+ *
+ * 2) For each dimension:
+ *
+ * - We sort the points.
+ * - Points that are "close enough" are considered to be in the same set.
+ * - We choose the set with more elements. If more than "threshold"
+ * points are in this set we use the first and the last point of the set
+ * to define the valid range for this dimension [min, max], otherwise we
+ * discard all the points and go to step 1.
+ *
+ * 3) We consider the unsorted S samples and try to feed them to the next
+ * filter in the chain. If one of the points of each sample
+ * is not in the allowed range for its dimension, we discard the sample.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/sort.h>
+#include <linux/ts_filter_group.h>
+
+static void ts_filter_group_clear_internal(struct ts_filter_group *tsfg,
+ int attempts)
+{
+ tsfg->N = 0;
+ tsfg->tries_left = attempts;
+}
+
+static void ts_filter_group_clear(struct ts_filter *tsf)
+{
+ struct ts_filter_group *tsfg = (struct ts_filter_group *)tsf;
+
+ ts_filter_group_clear_internal(tsfg, tsfg->config->attempts);
+
+ if (tsf->next) /* chain */
+ (tsf->next->api->clear)(tsf->next);
+}
+
+static struct ts_filter *ts_filter_group_create(void *conf, int count_coords)
+{
+ struct ts_filter_group *tsfg;
+ int i;
+
+ BUG_ON((count_coords < 1) || (count_coords > MAX_TS_FILTER_COORDS));
+
+ tsfg = kzalloc(sizeof(struct ts_filter_group), GFP_KERNEL);
+ if (!tsfg)
+ return NULL;
+
+ tsfg->config = (struct ts_filter_group_configuration *)conf;
+ tsfg->tsf.count_coords = count_coords;
+
+ BUG_ON(tsfg->config->attempts <= 0);
+
+ tsfg->samples[0] = kmalloc((2 + count_coords) * sizeof(int) *
+ tsfg->config->extent, GFP_KERNEL);
+ if (!tsfg->samples[0]) {
+ kfree(tsfg);
+ return NULL;
+ }
+ for (i = 1; i < count_coords; ++i)
+ tsfg->samples[i] = tsfg->samples[0] + i * tsfg->config->extent;
+ tsfg->sorted_samples = tsfg->samples[0] + count_coords *
+ tsfg->config->extent;
+ tsfg->group_size = tsfg->samples[0] + (1 + count_coords) *
+ tsfg->config->extent;
+
+ ts_filter_group_clear_internal(tsfg, tsfg->config->attempts);
+
+ printk(KERN_INFO" Created group ts filter len %d depth %d close %d "
+ "thresh %d\n", tsfg->config->extent, count_coords,
+ tsfg->config->close_enough, tsfg->config->threshold);
+
+ return &tsfg->tsf;
+}
+
+static void ts_filter_group_destroy(struct ts_filter *tsf)
+{
+ struct ts_filter_group *tsfg = (struct ts_filter_group *)tsf;
+
+ kfree(tsfg->samples[0]); /* first guy has pointer from kmalloc */
+ kfree(tsf);
+}
+
+static void ts_filter_group_scale(struct ts_filter *tsf, int *coords)
+{
+ if (tsf->next)
+ (tsf->next->api->scale)(tsf->next, coords);
+}
+
+static int int_cmp(const void *_a, const void *_b)
+{
+ const int *a = _a;
+ const int *b = _b;
+
+ if (*a > *b)
+ return 1;
+ if (*a < *b)
+ return -1;
+ return 0;
+}
+
+static int ts_filter_group_process(struct ts_filter *tsf, int *coords)
+{
+ struct ts_filter_group *tsfg = (struct ts_filter_group *)tsf;
+ int n;
+ int i;
+ int ret = 0; /* ask for more samples by default */
+
+ BUG_ON(tsfg->N >= tsfg->config->extent);
+
+ for (n = 0; n < tsf->count_coords; n++)
+ tsfg->samples[n][tsfg->N] = coords[n];
+
+ if (++tsfg->N < tsfg->config->extent)
+ return 0; /* we meed more samples */
+
+ for (n = 0; n < tsfg->tsf.count_coords; n++) {
+ int *v = tsfg->sorted_samples;
+ int ngroups = 0;
+ int best_size;
+ int best_idx = 0;
+ int idx = 0;
+
+ memcpy(v, tsfg->samples[n], tsfg->N * sizeof(int));
+ sort(v, tsfg->N, sizeof(int), int_cmp, NULL);
+
+ tsfg->group_size[0] = 1;
+ for (i = 1; i < tsfg->N; ++i) {
+ if (v[i] - v[i - 1] <= tsfg->config->close_enough)
+ tsfg->group_size[ngroups]++;
+ else
+ tsfg->group_size[++ngroups] = 1;
+ }
+ ngroups++;
+
+ best_size = tsfg->group_size[0];
+ for (i = 1; i < ngroups; i++) {
+ idx += tsfg->group_size[i - 1];
+ if (best_size < tsfg->group_size[i]) {
+ best_size = tsfg->group_size[i];
+ best_idx = idx;
+ }
+ }
+
+ if (best_size < tsfg->config->threshold) {
+ /* this set is not good enough for us */
+ if (--tsfg->tries_left) {
+ ts_filter_group_clear_internal
+ (tsfg, tsfg->tries_left);
+ return 0; /* ask for more samples */
+ }
+ return -1; /* we give up */
+ }
+
+ tsfg->range_min[n] = v[best_idx];
+ tsfg->range_max[n] = v[best_idx + best_size - 1];
+ }
+
+ BUG_ON(!tsf->next);
+
+ for (i = 0; i < tsfg->N; ++i) {
+ int r;
+
+ for (n = 0; n < tsfg->tsf.count_coords; ++n) {
+ coords[n] = tsfg->samples[n][i];
+ if (coords[n] < tsfg->range_min[n] ||
+ coords[n] > tsfg->range_max[n])
+ break;
+ }
+
+ if (n != tsfg->tsf.count_coords) /* sample not OK */
+ continue;
+
+ r = (tsf->next->api->process)(tsf->next, coords);
+ if (r) {
+ ret = r;
+ break;
+ }
+ }
+
+ ts_filter_group_clear_internal(tsfg, tsfg->config->attempts);
+
+ return ret;
+}
+
+struct ts_filter_api ts_filter_group_api = {
+ .create = ts_filter_group_create,
+ .destroy = ts_filter_group_destroy,
+ .clear = ts_filter_group_clear,
+ .process = ts_filter_group_process,
+ .scale = ts_filter_group_scale,
+};
+
diff --git a/drivers/input/touchscreen/ts_filter_variance.c b/drivers/input/touchscreen/ts_filter_variance.c
deleted file mode 100644
index c335210..0000000
--- a/drivers/input/touchscreen/ts_filter_variance.c
+++ /dev/null
@@ -1,205 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
- *
- * Copyright (C) 2008 by Openmoko, Inc.
- * Author: Nelson Castillo <arhuaco at freaks-unidos.net>
- * All rights reserved.
- *
- * This filter is useful to reject clicks that are not reliable. We
- * only care about what happens when we receive DOWN events for the fist time.
- * If this filter does not reject the first samples then it will change
- * its internal state to "passed" and the remaining samples
- * will be passed to the next filter in the chain.
- *
- * First we collect N samples, then then we sort them. We discard the borders
- * (with a window) and then compute the variance of the remaining set.
- * If the computed variance is bigger than a threshold, we reject the click.
- *
- */
-
-#include <linux/kernel.h>
-#include <linux/slab.h>
-#include <linux/sort.h>
-#include <linux/ts_filter_variance.h>
-
-static void ts_filter_variance_clear_internal(struct ts_filter_variance *tsfv,
- int attempts)
-{
- tsfv->N = 0;
- tsfv->passed = 0;
- tsfv->tries_left = attempts;
-}
-
-static void ts_filter_variance_clear(struct ts_filter *tsf)
-{
- struct ts_filter_variance *tsfv = (struct ts_filter_variance *)tsf;
-
- ts_filter_variance_clear_internal(tsfv, tsfv->config->attempts);
-
- if (tsf->next) /* chain */
- (tsf->next->api->clear)(tsf->next);
-}
-
-static struct ts_filter *ts_filter_variance_create(void *conf, int count_coords)
-{
- struct ts_filter_variance *tsfv;
- int i;
-
- BUG_ON((count_coords < 1) || (count_coords > MAX_TS_FILTER_COORDS));
-
- tsfv = kzalloc(sizeof(struct ts_filter_variance), GFP_KERNEL);
- if (!tsfv)
- return NULL;
-
- tsfv->config = (struct ts_filter_variance_configuration *)conf;
- tsfv->tsf.count_coords = count_coords;
-
- BUG_ON(tsfv->config->attempts <= 0);
-
- tsfv->samples[0] = kmalloc(count_coords * sizeof(int) *
- tsfv->config->extent, GFP_KERNEL);
- if (!tsfv->samples[0]) {
- kfree(tsfv);
- return NULL;
- }
- for (i = 1; i < count_coords; ++i)
- tsfv->samples[i] = tsfv->samples[0] + i * tsfv->config->extent;
-
- ts_filter_variance_clear_internal(tsfv, tsfv->config->attempts);
-
- printk(KERN_INFO" Created Variance ts filter len %d depth %d window"
- " %d thresh %d\n", tsfv->config->extent,
- count_coords, tsfv->config->window,
- tsfv->config->threshold);
-
- /* scale the threshold to avoid divisions later */
- tsfv->config->threshold *= tsfv->config->extent -
- (tsfv->config->window << 1);
-
- return &tsfv->tsf;
-}
-
-static void ts_filter_variance_destroy(struct ts_filter *tsf)
-{
- struct ts_filter_variance *tsfv = (struct ts_filter_variance *)tsf;
-
- kfree(tsfv->samples[0]); /* first guy has pointer from kmalloc */
- kfree(tsf);
-}
-
-static void ts_filter_variance_scale(struct ts_filter *tsf, int *coords)
-{
- struct ts_filter_variance *tsfv = (struct ts_filter_variance *)tsf;
-
- if (!tsfv->passed)
- return;
-
- if (tsf->next) {
- (tsf->next->api->scale)(tsf->next, coords);
- } else {
- int n;
- for (n = 0; n < tsf->count_coords; n++) {
- int c = tsfv->samples[n][tsfv->N / 2] +
- tsfv->samples[n][tsfv->N / 2 + 1] +
- tsfv->samples[n][tsfv->N / 2 - 1];
- coords[n] = (c + 2) / 3;
- }
- }
-}
-
-static int int_cmp(const void *_a, const void *_b)
-{
- const int *a = _a;
- const int *b = _b;
-
- if (*a > *b)
- return 1;
- if (*a < *b)
- return -1;
- return 0;
-}
-
-/* give us the raw sample data coords, and if we return 1 then you can
- * get a filtered coordinate from coords: if we return 0 you didn't
- * fill all the filters with samples yet.
- */
-
-static int ts_filter_variance_process(struct ts_filter *tsf, int *coords)
-{
- struct ts_filter_variance *tsfv = (struct ts_filter_variance *)tsf;
- int n;
-
- if (tsfv->passed) { /* chain */
- if (tsf->next)
- return (tsf->next->api->process)(tsf->next, coords);
- return 1;
- }
-
- for (n = 0; n < tsf->count_coords; n++)
- tsfv->samples[n][tsfv->N] = coords[n];
-
- if (++tsfv->N < tsfv->config->extent)
- return 0; /* we meed more samples */
-
- tsfv->passed = 1;
-
- for (n = 0; n < tsfv->tsf.count_coords; n++) {
- int i;
- int avg = 0;
- int variance = 0;
-
- sort(tsfv->samples[n], tsfv->config->extent, sizeof(int),
- int_cmp, NULL);
-
- for (i = tsfv->config->window; i < tsfv->config->extent -
- tsfv->config->window; ++i)
- avg += tsfv->samples[n][i];
-
- avg /= tsfv->config->extent - (tsfv->config->window << 1);
-
- for (i = tsfv->config->window; i < tsfv->config->extent -
- tsfv->config->window; ++i) {
- int s = tsfv->samples[n][i] - avg;
- variance += s * s;
- }
-
- if (variance > tsfv->config->threshold) {
- tsfv->passed = 0;
- break;
- }
- }
-
- if (tsfv->passed) /* Let's reuse the last sample */
- return ts_filter_variance_process(tsf, coords);
-
- if (--tsfv->tries_left) {
- ts_filter_variance_clear_internal(tsfv, tsfv->tries_left);
- return 0; /* ask for more samples */
- }
-
- /* avoid overflow if we are called again without clearing the filter */
- ts_filter_variance_clear_internal(tsfv, tsfv->config->attempts);
-
- return -1;
-}
-
-struct ts_filter_api ts_filter_variance_api = {
- .create = ts_filter_variance_create,
- .destroy = ts_filter_variance_destroy,
- .clear = ts_filter_variance_clear,
- .process = ts_filter_variance_process,
- .scale = ts_filter_variance_scale,
-};
-
diff --git a/include/linux/ts_filter.h b/include/linux/ts_filter.h
index 7262bba..bfb8a22 100644
--- a/include/linux/ts_filter.h
+++ b/include/linux/ts_filter.h
@@ -4,14 +4,11 @@
/*
* touchscreen filter
*
- * median
- *
* (c) 2008 Andy Green <andy at openmoko.com>
*/
-/* max filters you can chain up */
-#define MAX_TS_FILTER_CHAIN 4
-#define MAX_TS_FILTER_COORDS 6
+#define MAX_TS_FILTER_CHAIN 4 /* max filters you can chain up */
+#define MAX_TS_FILTER_COORDS 3 /* Y, Y and Z (pressure) */
struct ts_filter;
diff --git a/include/linux/ts_filter_group.h b/include/linux/ts_filter_group.h
new file mode 100644
index 0000000..1e74c8d
--- /dev/null
+++ b/include/linux/ts_filter_group.h
@@ -0,0 +1,39 @@
+#ifndef __TS_FILTER_GROUP_H__
+#define __TS_FILTER_GROUP_H__
+
+#include <linux/ts_filter.h>
+
+/*
+ * Touchscreen group filter.
+ *
+ * Copyright (C) 2008 by Openmoko, Inc.
+ * Author: Nelson Castillo <arhuaco at freaks-unidos.net>
+ *
+ */
+
+struct ts_filter_group_configuration {
+ int extent;
+ int close_enough;
+ int threshold;
+ int attempts;
+};
+
+struct ts_filter_group {
+ struct ts_filter tsf;
+ struct ts_filter_group_configuration *config;
+
+ int N; /* How many samples we have */
+ int *samples[MAX_TS_FILTER_COORDS]; /* the samples, our input */
+
+ int *group_size; /* used for temporal computations */
+ int *sorted_samples; /* used for temporal computations */
+
+ int range_max[MAX_TS_FILTER_COORDS]; /* max computed ranges */
+ int range_min[MAX_TS_FILTER_COORDS]; /* min computed ranges */
+
+ int tries_left; /* We finish if we don't get enough samples */
+};
+
+extern struct ts_filter_api ts_filter_group_api;
+
+#endif
diff --git a/include/linux/ts_filter_variance.h b/include/linux/ts_filter_variance.h
deleted file mode 100644
index 574cf90..0000000
--- a/include/linux/ts_filter_variance.h
+++ /dev/null
@@ -1,36 +0,0 @@
-#ifndef __TS_FILTER_VARIANCE_H__
-#define __TS_FILTER_VARIANCE_H__
-
-#include <linux/ts_filter.h>
-
-/*
- * touchscreen filter
- *
- * Variance
- *
- * Copyright (C) 2008 by Openmoko, Inc.
- * Author: Nelson Castillo <arhuaco at freaks-unidos.net>
- *
- */
-
-struct ts_filter_variance_configuration {
- int extent;
- int window;
- int threshold;
- int attempts;
-};
-
-struct ts_filter_variance {
- struct ts_filter tsf;
- struct ts_filter_variance_configuration *config;
-
- int *samples[2];
- int N; /* How many samples we have */
-
- int tries_left; /* How many times we can try to get a point */
- int passed; /* Did the samples pass the test? */
-};
-
-extern struct ts_filter_api ts_filter_variance_api;
-
-#endif
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