[PATCH v1] touchscreen/88pm860x-ts: check the pm860x_set_bits return value

[PATCH v1] touchscreen/88pm860x-ts: check the pm860x_set_bits return value

[Li Zhong]

pm860x_touch_close() got the return value of pm860x_set_bits() but
didn't check it. However, pm860x_set_bits() could fail when writing the
reg map fails. Since pm860x_touch_close() cannot return an error value,
we retry the bit setting in the error handling.

Signed-off-by: Li Zhong <floridsleeves@gmail.com>
---
 drivers/input/touchscreen/88pm860x-ts.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/input/touchscreen/88pm860x-ts.c b/drivers/input/touchscreen/88pm860x-ts.c
index 81a3ea4b9a3d..043520d1ff26 100644
--- a/drivers/input/touchscreen/88pm860x-ts.c
+++ b/drivers/input/touchscreen/88pm860x-ts.c
@@ -106,10 +106,13 @@ static void pm860x_touch_close(struct input_dev *dev)
 {
 	struct pm860x_touch *touch = input_get_drvdata(dev);
 	int data;
+	int ret;
 
 	data = MEAS_PD_EN | MEAS_TSIX_EN | MEAS_TSIY_EN
 		| MEAS_TSIZ1_EN | MEAS_TSIZ2_EN;
-	pm860x_set_bits(touch->i2c, MEAS_EN3, data, 0);
+	ret = pm860x_set_bits(touch->i2c, MEAS_EN3, data, 0);
+	if (ret < 0)
+		pm860x_set_bits(touch->i2c, MEAS_EN3, data, 0);
 }
 
 #ifdef CONFIG_OF
-- 
2.25.1

Re: [PATCH v1] touchscreen/88pm860x-ts: check the pm860x_set_bits return value

[Dmitry Torokhov]

Hi,

On Wed, Sep 21, 2022 at 01:37:06PM -0700, Li Zhong wrote:
> pm860x_touch_close() got the return value of pm860x_set_bits() but
> didn't check it. However, pm860x_set_bits() could fail when writing the
> reg map fails.

Under what conditions would the write fail?

> Since pm860x_touch_close() cannot return an error value,
> we retry the bit setting in the error handling.

What guarantees that the repeated write will not fail again? What is the
failure mode if write does not succeed?


> 
> Signed-off-by: Li Zhong <floridsleeves@gmail.com>
> ---
>  drivers/input/touchscreen/88pm860x-ts.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/input/touchscreen/88pm860x-ts.c b/drivers/input/touchscreen/88pm860x-ts.c
> index 81a3ea4b9a3d..043520d1ff26 100644
> --- a/drivers/input/touchscreen/88pm860x-ts.c
> +++ b/drivers/input/touchscreen/88pm860x-ts.c
> @@ -106,10 +106,13 @@ static void pm860x_touch_close(struct input_dev *dev)
>  {
>  	struct pm860x_touch *touch = input_get_drvdata(dev);
>  	int data;
> +	int ret;
>  
>  	data = MEAS_PD_EN | MEAS_TSIX_EN | MEAS_TSIY_EN
>  		| MEAS_TSIZ1_EN | MEAS_TSIZ2_EN;
> -	pm860x_set_bits(touch->i2c, MEAS_EN3, data, 0);
> +	ret = pm860x_set_bits(touch->i2c, MEAS_EN3, data, 0);
> +	if (ret < 0)
> +		pm860x_set_bits(touch->i2c, MEAS_EN3, data, 0);
>  }
>  
>  #ifdef CONFIG_OF
> -- 
> 2.25.1
> 

Thanks.

-- 
Dmitry