2020-10-28 07:01:41

by Oleksij Rempel

[permalink] [raw]
Subject: [PATCH v2] Input: touchscreen: ads7846.c: Fix race that causes missing releases

From: David Jander <[email protected]>

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 <[email protected]>
Signed-off-by: David Jander <[email protected]>
Signed-off-by: Oleksij Rempel <[email protected]>
---
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


2020-11-09 11:03:43

by Oleksij Rempel

[permalink] [raw]
Subject: Re: [PATCH v2] Input: touchscreen: ads7846.c: Fix race that causes missing releases

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 <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: David Jander <[email protected]>
> Signed-off-by: Oleksij Rempel <[email protected]>
> ---
> 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
>
>

--
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 |

2020-11-11 19:09:47

by Dmitry Torokhov

[permalink] [raw]
Subject: Re: [PATCH v2] Input: touchscreen: ads7846.c: Fix race that causes missing releases

Hi Oleksij,

On Tue, Oct 27, 2020 at 11:54:16AM +0100, Oleksij Rempel wrote:
> From: David Jander <[email protected]>
>
> 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 <[email protected]>

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 <[email protected]>
> Signed-off-by: Oleksij Rempel <[email protected]>

Thanks.

--
Dmitry

2020-11-12 11:52:01

by Oleksij Rempel

[permalink] [raw]
Subject: Re: [PATCH v2] Input: touchscreen: ads7846.c: Fix race that causes missing releases

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 <[email protected]>
> >
> > 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 <[email protected]>
>
> 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 <[email protected]>
> > Signed-off-by: Oleksij Rempel <[email protected]>

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 |

2020-11-18 00:33:26

by Dmitry Torokhov

[permalink] [raw]
Subject: Re: [PATCH v2] Input: touchscreen: ads7846.c: Fix race that causes missing releases

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 <[email protected]>
> > >
> > > 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 <[email protected]>
> >
> > 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