[PATCH] backlight: pwm_bl: fix devicetree parsing with auto-generated brightness tables

[PATCH] backlight: pwm_bl: fix devicetree parsing with auto-generated brightness tables

[Heiko Stuebner]

From: Heiko Stuebner <heiko.stuebner@bq.com>

Commit 88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly
to human eye") made the parse-dt function return early when using an auto-
generated brightness-table, but didn't take into account that some more
settings were handled below the brightness handling, like power-on-delays
and also setting the pdata enable-gpio to -EINVAL.

This surfaces for example in the case of a backlight without any
enable-gpio which then tries to use gpio-0 in error.

Fix this by simply moving the trailing settings above the brightness
handling.

Fixes: 88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly to human eye")
Signed-off-by: Heiko Stuebner <heiko.stuebner@bq.com>
---
 drivers/video/backlight/pwm_bl.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index bcd08b41765d..b7b5b31f3824 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -272,6 +272,16 @@ static int pwm_backlight_parse_dt(struct device *dev,
 
 	memset(data, 0, sizeof(*data));
 
+	/*
+	 * These values are optional and set as 0 by default, the out values
+	 * are modified only if a valid u32 value can be decoded.
+	 */
+	of_property_read_u32(node, "post-pwm-on-delay-ms",
+			     &data->post_pwm_on_delay);
+	of_property_read_u32(node, "pwm-off-delay-ms", &data->pwm_off_delay);
+
+	data->enable_gpio = -EINVAL;
+
 	/*
 	 * Determine the number of brightness levels, if this property is not
 	 * set a default table of brightness levels will be used.
@@ -384,15 +394,6 @@ static int pwm_backlight_parse_dt(struct device *dev,
 		data->max_brightness--;
 	}
 
-	/*
-	 * These values are optional and set as 0 by default, the out values
-	 * are modified only if a valid u32 value can be decoded.
-	 */
-	of_property_read_u32(node, "post-pwm-on-delay-ms",
-			     &data->post_pwm_on_delay);
-	of_property_read_u32(node, "pwm-off-delay-ms", &data->pwm_off_delay);
-
-	data->enable_gpio = -EINVAL;
 	return 0;
 }
 
-- 
2.18.0

Re: [PATCH] backlight: pwm_bl: fix devicetree parsing with auto-generated brightness tables

[Daniel Thompson]

On Mon, Nov 12, 2018 at 10:02:57AM +0100, Heiko Stuebner wrote:
> From: Heiko Stuebner <heiko.stuebner@bq.com>
> 
> Commit 88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly
> to human eye") made the parse-dt function return early when using an auto-
> generated brightness-table, but didn't take into account that some more
> settings were handled below the brightness handling, like power-on-delays
> and also setting the pdata enable-gpio to -EINVAL.
> 
> This surfaces for example in the case of a backlight without any
> enable-gpio which then tries to use gpio-0 in error.
> 
> Fix this by simply moving the trailing settings above the brightness
> handling.
> 
> Fixes: 88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly to human eye")
> Signed-off-by: Heiko Stuebner <heiko.stuebner@bq.com>

Acked-by: Daniel Thompson <daniel.thompson@linaro.org>

> ---
>  drivers/video/backlight/pwm_bl.c | 19 ++++++++++---------
>  1 file changed, 10 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
> index bcd08b41765d..b7b5b31f3824 100644
> --- a/drivers/video/backlight/pwm_bl.c
> +++ b/drivers/video/backlight/pwm_bl.c
> @@ -272,6 +272,16 @@ static int pwm_backlight_parse_dt(struct device *dev,
>  
>  	memset(data, 0, sizeof(*data));
>  
> +	/*
> +	 * These values are optional and set as 0 by default, the out values
> +	 * are modified only if a valid u32 value can be decoded.
> +	 */
> +	of_property_read_u32(node, "post-pwm-on-delay-ms",
> +			     &data->post_pwm_on_delay);
> +	of_property_read_u32(node, "pwm-off-delay-ms", &data->pwm_off_delay);
> +
> +	data->enable_gpio = -EINVAL;
> +
>  	/*
>  	 * Determine the number of brightness levels, if this property is not
>  	 * set a default table of brightness levels will be used.
> @@ -384,15 +394,6 @@ static int pwm_backlight_parse_dt(struct device *dev,
>  		data->max_brightness--;
>  	}
>  
> -	/*
> -	 * These values are optional and set as 0 by default, the out values
> -	 * are modified only if a valid u32 value can be decoded.
> -	 */
> -	of_property_read_u32(node, "post-pwm-on-delay-ms",
> -			     &data->post_pwm_on_delay);
> -	of_property_read_u32(node, "pwm-off-delay-ms", &data->pwm_off_delay);
> -
> -	data->enable_gpio = -EINVAL;
>  	return 0;
>  }
>  
> -- 
> 2.18.0
>