diff mbox series

[v2] Input: touchscreen: ads7846.c: Fix race that causes missing releases

Message ID 20201027105416.18773-1-o.rempel@pengutronix.de
State New
Headers show
Series [v2] Input: touchscreen: ads7846.c: Fix race that causes missing releases | expand

Commit Message

Oleksij Rempel Oct. 27, 2020, 10:54 a.m. UTC 
From: David Jander <david@protonic.nl>

If touchscreen is released while busy reading HWMON device, the release
can be missed. The IRQ thread is not started because no touch is active
and BTN_TOUCH release event is never sent.

Fixes: f5a28a7d4858f94a ("Input: ads7846 - avoid pen up/down when reading hwmon")
Co-Developed-by: David Jander <david@protonic.nl>
Signed-off-by: David Jander <david@protonic.nl>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/input/touchscreen/ads7846.c | 44 +++++++++++++++++------------
 1 file changed, 26 insertions(+), 18 deletions(-)

Comments

Oleksij Rempel Nov. 9, 2020, 11 a.m. UTC | #1 
Hello Dmitry,

ping for this patch. Are there some changes needed?

Regards,
Oleksij

On Tue, Oct 27, 2020 at 11:54:16AM +0100, Oleksij Rempel wrote:
> From: David Jander <david@protonic.nl>

> 

> If touchscreen is released while busy reading HWMON device, the release

> can be missed. The IRQ thread is not started because no touch is active

> and BTN_TOUCH release event is never sent.

> 

> Fixes: f5a28a7d4858f94a ("Input: ads7846 - avoid pen up/down when reading hwmon")

> Co-Developed-by: David Jander <david@protonic.nl>

> Signed-off-by: David Jander <david@protonic.nl>

> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>

> ---

>  drivers/input/touchscreen/ads7846.c | 44 +++++++++++++++++------------

>  1 file changed, 26 insertions(+), 18 deletions(-)

> 

> diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c

> index f2dc2c8ab5ec..4164a9834b59 100644

> --- a/drivers/input/touchscreen/ads7846.c

> +++ b/drivers/input/touchscreen/ads7846.c

> @@ -199,6 +199,26 @@ struct ads7846 {

>  #define	REF_ON	(READ_12BIT_DFR(x, 1, 1))

>  #define	REF_OFF	(READ_12BIT_DFR(y, 0, 0))

>  

> +static int get_pendown_state(struct ads7846 *ts)

> +{

> +	if (ts->get_pendown_state)

> +		return ts->get_pendown_state();

> +

> +	return !gpio_get_value(ts->gpio_pendown);

> +}

> +

> +static void ads7846_report_pen_up(struct ads7846 *ts)

> +{

> +	struct input_dev *input = ts->input;

> +

> +	input_report_key(input, BTN_TOUCH, 0);

> +	input_report_abs(input, ABS_PRESSURE, 0);

> +	input_sync(input);

> +

> +	ts->pendown = false;

> +	dev_vdbg(&ts->spi->dev, "UP\n");

> +}

> +

>  /* Must be called with ts->lock held */

>  static void ads7846_stop(struct ads7846 *ts)

>  {

> @@ -215,6 +235,10 @@ static void ads7846_stop(struct ads7846 *ts)

>  static void ads7846_restart(struct ads7846 *ts)

>  {

>  	if (!ts->disabled && !ts->suspended) {

> +		/* Check if pen was released since last stop */

> +		if (ts->pendown && !get_pendown_state(ts))

> +			ads7846_report_pen_up(ts);

> +

>  		/* Tell IRQ thread that it may poll the device. */

>  		ts->stopped = false;

>  		mb();

> @@ -606,14 +630,6 @@ static const struct attribute_group ads784x_attr_group = {

>  

>  /*--------------------------------------------------------------------------*/

>  

> -static int get_pendown_state(struct ads7846 *ts)

> -{

> -	if (ts->get_pendown_state)

> -		return ts->get_pendown_state();

> -

> -	return !gpio_get_value(ts->gpio_pendown);

> -}

> -

>  static void null_wait_for_sync(void)

>  {

>  }

> @@ -868,16 +884,8 @@ static irqreturn_t ads7846_irq(int irq, void *handle)

>  				   msecs_to_jiffies(TS_POLL_PERIOD));

>  	}

>  

> -	if (ts->pendown && !ts->stopped) {

> -		struct input_dev *input = ts->input;

> -

> -		input_report_key(input, BTN_TOUCH, 0);

> -		input_report_abs(input, ABS_PRESSURE, 0);

> -		input_sync(input);

> -

> -		ts->pendown = false;

> -		dev_vdbg(&ts->spi->dev, "UP\n");

> -	}

> +	if (ts->pendown && !ts->stopped)

> +		ads7846_report_pen_up(ts);

>  

>  	return IRQ_HANDLED;

>  }

> -- 

> 2.28.0

> 

> 


-- 
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Dmitry Torokhov Nov. 11, 2020, 7:07 p.m. UTC | #2 
Hi Oleksij,

On Tue, Oct 27, 2020 at 11:54:16AM +0100, Oleksij Rempel wrote:
> From: David Jander <david@protonic.nl>

> 

> If touchscreen is released while busy reading HWMON device, the release

> can be missed. The IRQ thread is not started because no touch is active

> and BTN_TOUCH release event is never sent.

> 

> Fixes: f5a28a7d4858f94a ("Input: ads7846 - avoid pen up/down when reading hwmon")

> Co-Developed-by: David Jander <david@protonic.nl>


Since the patch is nominally attributed to David (via the From: tag)
I'll be changing Co-developed-by tag to your name, OK?

> Signed-off-by: David Jander <david@protonic.nl>

> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>


Thanks.

-- 
Dmitry
Oleksij Rempel Nov. 12, 2020, 11:48 a.m. UTC | #3 
On Wed, Nov 11, 2020 at 11:07:40AM -0800, Dmitry Torokhov wrote:
> Hi Oleksij,

> 

> On Tue, Oct 27, 2020 at 11:54:16AM +0100, Oleksij Rempel wrote:

> > From: David Jander <david@protonic.nl>

> > 

> > If touchscreen is released while busy reading HWMON device, the release

> > can be missed. The IRQ thread is not started because no touch is active

> > and BTN_TOUCH release event is never sent.

> > 

> > Fixes: f5a28a7d4858f94a ("Input: ads7846 - avoid pen up/down when reading hwmon")

> > Co-Developed-by: David Jander <david@protonic.nl>

> 

> Since the patch is nominally attributed to David (via the From: tag)

> I'll be changing Co-developed-by tag to your name, OK?


OK.

> 

> > Signed-off-by: David Jander <david@protonic.nl>

> > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>


Regards,
Oleksij

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
Dmitry Torokhov Nov. 18, 2020, 12:31 a.m. UTC | #4 
On Thu, Nov 12, 2020 at 12:48:51PM +0100, Oleksij Rempel wrote:
> On Wed, Nov 11, 2020 at 11:07:40AM -0800, Dmitry Torokhov wrote:

> > Hi Oleksij,

> > 

> > On Tue, Oct 27, 2020 at 11:54:16AM +0100, Oleksij Rempel wrote:

> > > From: David Jander <david@protonic.nl>

> > > 

> > > If touchscreen is released while busy reading HWMON device, the release

> > > can be missed. The IRQ thread is not started because no touch is active

> > > and BTN_TOUCH release event is never sent.

> > > 

> > > Fixes: f5a28a7d4858f94a ("Input: ads7846 - avoid pen up/down when reading hwmon")

> > > Co-Developed-by: David Jander <david@protonic.nl>

> > 

> > Since the patch is nominally attributed to David (via the From: tag)

> > I'll be changing Co-developed-by tag to your name, OK?

> 

> OK.


Applied, thank you.

-- 
Dmitry
diff mbox series

Patch

diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index f2dc2c8ab5ec..4164a9834b59 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -199,6 +199,26 @@  struct ads7846 {
 #define	REF_ON	(READ_12BIT_DFR(x, 1, 1))
 #define	REF_OFF	(READ_12BIT_DFR(y, 0, 0))
 
+static int get_pendown_state(struct ads7846 *ts)
+{
+	if (ts->get_pendown_state)
+		return ts->get_pendown_state();
+
+	return !gpio_get_value(ts->gpio_pendown);
+}
+
+static void ads7846_report_pen_up(struct ads7846 *ts)
+{
+	struct input_dev *input = ts->input;
+
+	input_report_key(input, BTN_TOUCH, 0);
+	input_report_abs(input, ABS_PRESSURE, 0);
+	input_sync(input);
+
+	ts->pendown = false;
+	dev_vdbg(&ts->spi->dev, "UP\n");
+}
+
 /* Must be called with ts->lock held */
 static void ads7846_stop(struct ads7846 *ts)
 {
@@ -215,6 +235,10 @@  static void ads7846_stop(struct ads7846 *ts)
 static void ads7846_restart(struct ads7846 *ts)
 {
 	if (!ts->disabled && !ts->suspended) {
+		/* Check if pen was released since last stop */
+		if (ts->pendown && !get_pendown_state(ts))
+			ads7846_report_pen_up(ts);
+
 		/* Tell IRQ thread that it may poll the device. */
 		ts->stopped = false;
 		mb();
@@ -606,14 +630,6 @@  static const struct attribute_group ads784x_attr_group = {
 
 /*--------------------------------------------------------------------------*/
 
-static int get_pendown_state(struct ads7846 *ts)
-{
-	if (ts->get_pendown_state)
-		return ts->get_pendown_state();
-
-	return !gpio_get_value(ts->gpio_pendown);
-}
-
 static void null_wait_for_sync(void)
 {
 }
@@ -868,16 +884,8 @@  static irqreturn_t ads7846_irq(int irq, void *handle)
 				   msecs_to_jiffies(TS_POLL_PERIOD));
 	}
 
-	if (ts->pendown && !ts->stopped) {
-		struct input_dev *input = ts->input;
-
-		input_report_key(input, BTN_TOUCH, 0);
-		input_report_abs(input, ABS_PRESSURE, 0);
-		input_sync(input);
-
-		ts->pendown = false;
-		dev_vdbg(&ts->spi->dev, "UP\n");
-	}
+	if (ts->pendown && !ts->stopped)
+		ads7846_report_pen_up(ts);
 
 	return IRQ_HANDLED;
 }