[PATCH v8 1/5] Input: stmfts - wait for controller ready after reset
Dmitry Torokhov
dmitry.torokhov at gmail.com
Fri Sep 25 15:18:10 PDT 2026
On Fri, Sep 25, 2026 at 11:22:19PM +0200, David Heidelberg via B4 Relay wrote:
> From: David Heidelberg <david at ixit.cz>
>
> After releasing the reset line stmfts_reset() sleeps a fixed 50 ms and
> stmfts_power_on() another 50 ms before the first I2C access. That is
> enough for a warm reset, but when both supplies were really cut during
> system suspend the controller boots from cold and can need longer. If
> it does, the first read fails, stmfts_resume() returns an error and the
> touchscreen is left powered off with its interrupt disabled.
>
> The controller posts a controller ready event once it has booted, and
> the event parser already completes cmd_done on it. Enable the interrupt
> right after releasing reset and wait for that event instead of sleeping,
> giving the controller 300 ms, the total budget the vendor driver allows.
> Boards without a reset line keep the old timing.
>
> Usually phones such as Pixel 4a and Xiaomi Mi 8 needs longer delay, so
> without this change touchscreen stops working.
>
> Fixes: 8a1f9de80e45 ("Input: stmfts - add optional reset GPIO support")
> Cc: stable at vger.kernel.org
> Co-developed-by: Dmitry Torokhov <dmitry.torokhov at gmail.com>
> Signed-off-by: David Heidelberg <david at ixit.cz>
> ---
> drivers/input/touchscreen/stmfts.c | 60 ++++++++++++++++++++++++--------------
> 1 file changed, 38 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/input/touchscreen/stmfts.c b/drivers/input/touchscreen/stmfts.c
> index 972687797f826..1720202d6186b 100644
> --- a/drivers/input/touchscreen/stmfts.c
> +++ b/drivers/input/touchscreen/stmfts.c
> @@ -59,16 +59,18 @@
> #define STMFTS_MASK_X_MSB 0x0f
> #define STMFTS_MASK_Y_LSB 0xf0
>
> /* key related event masks */
> #define STMFTS_MASK_KEY_NO_TOUCH 0x00
> #define STMFTS_MASK_KEY_MENU 0x01
> #define STMFTS_MASK_KEY_BACK 0x02
>
> +#define STMFTS_RESET_TIMEOUT_MS 300
> +
> #define STMFTS_EVENT_SIZE 8
> #define STMFTS_STACK_DEPTH 32
> #define STMFTS_DATA_MAX_SIZE (STMFTS_EVENT_SIZE * STMFTS_STACK_DEPTH)
> #define STMFTS_MAX_FINGERS 10
> #define STMFTS_DEV_NAME "stmfts"
>
> static const struct regulator_bulk_data stmfts_supplies[] = {
> { .supply = "vdd" },
> @@ -538,25 +540,16 @@ static int stmfts_read_system_info(struct stmfts_data *sdata)
> sdata->chip_ver = reg[0];
> sdata->fw_ver = be16_to_cpup((__be16 *)®[2]);
> sdata->config_id = reg[4];
> sdata->config_ver = reg[5];
>
> return 0;
> }
>
> -static void stmfts_reset(struct stmfts_data *sdata)
> -{
> - gpiod_set_value_cansleep(sdata->reset_gpio, 1);
> - msleep(20);
> -
> - gpiod_set_value_cansleep(sdata->reset_gpio, 0);
> - msleep(50);
> -}
> -
> static int stmfts_configure(struct stmfts_data *sdata)
> {
> int err;
>
> err = stmfts_command(sdata, STMFTS_SYSTEM_RESET);
> if (err)
> return err;
>
> @@ -582,53 +575,76 @@ static int stmfts_configure(struct stmfts_data *sdata)
>
> return 0;
> }
>
> static int stmfts_power_on(struct stmfts_data *sdata)
> {
> int err;
>
> + if (sdata->reset_gpio) {
> + gpiod_set_value_cansleep(sdata->reset_gpio, 1);
> + /* a short delay before powering up */
> + usleep_range(1000, 1500);
> + }
> +
> err = regulator_bulk_enable(ARRAY_SIZE(stmfts_supplies),
> sdata->supplies);
> if (err)
> return err;
>
> - /*
> - * The datasheet does not specify the power on time, but considering
> - * that the reset time is < 10ms, I sleep 20ms to be sure
> - */
> - msleep(20);
> + if (sdata->reset_gpio) {
> + reinit_completion(&sdata->cmd_done);
>
> - if (sdata->reset_gpio)
> - stmfts_reset(sdata);
> + /*
> + * The datasheet does not specify the power on time, but
> + * considering that the reset time is < 10ms, sleep for 20ms
> + * to be sure before releasing reset line.
> + */
> + msleep(20);
> + gpiod_set_value_cansleep(sdata->reset_gpio, 0);
>
> - err = stmfts_read_system_info(sdata);
> - if (err)
> - goto err_disable_regulators;
> + enable_irq(sdata->client->irq);
>
> - enable_irq(sdata->client->irq);
> + if (!wait_for_completion_timeout(&sdata->cmd_done,
> + msecs_to_jiffies(STMFTS_RESET_TIMEOUT_MS))) {
> + dev_err(&sdata->client->dev, "controller not ready after reset");
> + err = -ETIMEDOUT;
> + goto err_disable_irq;
> + }
> + } else {
> + /*
> + * We do not know the real controller state (was it powered
> + * off or reset). Let's hope that this is enough time to
> + * initialize.
> + */
> + msleep(70);
> +
> + enable_irq(sdata->client->irq);
Sashiko gave me an idea. What if we do this:
diff --git a/drivers/input/touchscreen/stmfts.c b/drivers/input/touchscreen/stmfts.c
index 1720202d6186..e147a27f57b3 100644
--- a/drivers/input/touchscreen/stmfts.c
+++ b/drivers/input/touchscreen/stmfts.c
@@ -578,6 +578,7 @@ static int stmfts_configure(struct stmfts_data *sdata)
static int stmfts_power_on(struct stmfts_data *sdata)
{
+ unsigned int timeout;
int err;
if (sdata->reset_gpio) {
@@ -591,9 +592,9 @@ static int stmfts_power_on(struct stmfts_data *sdata)
if (err)
return err;
- if (sdata->reset_gpio) {
- reinit_completion(&sdata->cmd_done);
+ reinit_completion(&sdata->cmd_done);
+ if (sdata->reset_gpio) {
/*
* The datasheet does not specify the power on time, but
* considering that the reset time is < 10ms, sleep for 20ms
@@ -602,23 +603,29 @@ static int stmfts_power_on(struct stmfts_data *sdata)
msleep(20);
gpiod_set_value_cansleep(sdata->reset_gpio, 0);
- enable_irq(sdata->client->irq);
-
- if (!wait_for_completion_timeout(&sdata->cmd_done,
- msecs_to_jiffies(STMFTS_RESET_TIMEOUT_MS))) {
- dev_err(&sdata->client->dev, "controller not ready after reset");
- err = -ETIMEDOUT;
- goto err_disable_irq;
- }
+ timeout = STMFTS_RESET_TIMEOUT_MS;
} else {
/*
* We do not know the real controller state (was it powered
* off or reset). Let's hope that this is enough time to
* initialize.
*/
- msleep(70);
+ timeout = 70;
+ }
- enable_irq(sdata->client->irq);
+ enable_irq(sdata->client->irq);
+
+ if (!wait_for_completion_timeout(&sdata->cmd_done,
+ msecs_to_jiffies(timeout))) {
+ if (sdata->reset_gpio) {
+ dev_err(&sdata->client->dev, "controller not ready after reset");
+ err = -ETIMEDOUT;
+ goto err_disable_irq;
+ }
+ /*
+ * If we did not reset the countroller ourselves continue
+ * even if we did not receive "ready" message.
+ */
}
err = stmfts_read_system_info(sdata);
No need to resend the series unless there is more feedback on the
bindings.
Thanks.
--
Dmitry
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