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From dd802fc03b1c71b4297e87068077bfcf9810300a Mon Sep 17 00:00:00 2001
From: Nick Hollinghurst <nick.hollinghurst@raspberrypi.com>
Date: Wed, 11 Oct 2023 15:14:59 +0100
Subject: [PATCH] input: touchscreen: edt-ft5x06: Suppress bogus data on
startup
When polled without the use of IRQ, FT5x06 registers may return
undefined initial data, causing unwanted touches or event spamming.
A simple way to filter this out is to suppress touches until the
TD_STATUS register changes for the first time.
Increase the delay before first polling to 300ms, to avoid
transient I2C read flakiness that seems to occur after reset.
Signed-off-by: Nick Hollinghurst <nick.hollinghurst@raspberrypi.com>
---
drivers/input/touchscreen/edt-ft5x06.c | 31 +++++++++++++++++++++++---
1 file changed, 28 insertions(+), 3 deletions(-)
--- a/drivers/input/touchscreen/edt-ft5x06.c
+++ b/drivers/input/touchscreen/edt-ft5x06.c
@@ -75,6 +75,8 @@
#define EDT_DEFAULT_NUM_X 1024
#define EDT_DEFAULT_NUM_Y 1024
+#define RESET_DELAY_MS 300 /* reset deassert to I2C */
+#define FIRST_POLL_DELAY_MS 300 /* in addition to the above */
#define POLL_INTERVAL_MS 17 /* 17ms = 60fps */
enum edt_pmode {
@@ -134,6 +136,7 @@ struct edt_ft5x06_ts_data {
char name[EDT_NAME_LEN];
char fw_version[EDT_NAME_LEN];
+ int init_td_status;
struct edt_reg_addr reg_addr;
enum edt_ver version;
@@ -268,12 +271,33 @@ static irqreturn_t edt_ft5x06_ts_isr(int
* points.
*/
num_points = min(rdbuf[2] & 0xf, tsdata->max_support_points);
+
+ /* When polling FT5x06 without IRQ: initial register contents
+ * could be stale or undefined; discard all readings until
+ * TD_STATUS changes for the first time (or num_points is 0).
+ */
+ if (tsdata->init_td_status) {
+ if (tsdata->init_td_status < 0)
+ tsdata->init_td_status = rdbuf[2];
+
+ if (num_points && rdbuf[2] == tsdata->init_td_status)
+ goto out;
+
+ tsdata->init_td_status = 0;
+ }
+
if (num_points) {
datalen = tplen * num_points + crclen;
cmd = offset;
error = edt_ft5x06_ts_readwrite(tsdata->client,
sizeof(cmd), &cmd,
datalen, &rdbuf[offset]);
+ if (error) {
+ dev_err_ratelimited(dev,
+ "Unable to fetch data, error: %d\n",
+ error);
+ goto out;
+ }
}
}
@@ -1294,7 +1318,7 @@ static int edt_ft5x06_ts_probe(struct i2
if (tsdata->reset_gpio) {
usleep_range(5000, 6000);
gpiod_set_value_cansleep(tsdata->reset_gpio, 0);
- msleep(300);
+ msleep(RESET_DELAY_MS);
}
input = devm_input_allocate_device(&client->dev);
@@ -1384,11 +1408,12 @@ static int edt_ft5x06_ts_probe(struct i2
return error;
}
} else {
+ tsdata->init_td_status = -1; /* filter bogus initial data */
INIT_WORK(&tsdata->work_i2c_poll,
edt_ft5x06_ts_work_i2c_poll);
timer_setup(&tsdata->timer, edt_ft5x06_ts_irq_poll_timer, 0);
- tsdata->timer.expires = jiffies +
- msecs_to_jiffies(POLL_INTERVAL_MS);
+ tsdata->timer.expires =
+ jiffies + msecs_to_jiffies(FIRST_POLL_DELAY_MS);
add_timer(&tsdata->timer);
}
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