Re: [PATCH v4 1/3] ACPI video: Fix brightness control initialization for some laptops.

[Rafael J. Wysocki]

On Tuesday, March 19, 2013 05:22:50 PM Danny Baumann wrote:
> In particular, this fixes brightness control initialization for all
> devices that return index values from _BQC and don't happen to have the
> initial index set by the BIOS in their _BCL table. One example for that
> is the Dell Inspiron 15R SE (model number 7520).
> 
> What happened for those devices is that acpi_init_brightness queried the
> initial brightness by calling acpi_video_device_lcd_get_level_current.
> This called _BQC, which returned e.g. 13. As _BQC_use_index isn't
> determined at this point (and thus has its initial value of 0), the
> index isn't converted into the actual level. As '13' isn't present in
> the _BCL list, *level is later overwritten with brightness->curr, which
> was initialized to max_level (100) before. Later in
> acpi_init_brightness, level_old (with the value 100) is used as an index
> into the _BCL table, which causes a value outside of the actual table to
> be used as input into acpi_video_device_lcd_set_level(). Depending on
> the (undefined) value of that location, this call will fail, causing the
> brightness control for the device in question not to be enabled.
> 
> Fix that by returning the raw value returned by the _BQC call in the
> initialization case.
> 
> Signed-off-by: Danny Baumann <dannybaumann@xxxxxx>

All patches in the series applied to linux-pm.git/linux-next.

Thanks,
Rafael


> ---
>  drivers/acpi/video.c | 43 ++++++++++++++++++++++++++-----------------
>  1 file changed, 26 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
> index 313f959..09e4722 100644
> --- a/drivers/acpi/video.c
> +++ b/drivers/acpi/video.c
> @@ -222,7 +222,7 @@ static int acpi_video_device_lcd_set_level(struct acpi_video_device *device,
>  			int level);
>  static int acpi_video_device_lcd_get_level_current(
>  			struct acpi_video_device *device,
> -			unsigned long long *level, int init);
> +			unsigned long long *level, bool raw);
>  static int acpi_video_get_next_level(struct acpi_video_device *device,
>  				     u32 level_current, u32 event);
>  static int acpi_video_switch_brightness(struct acpi_video_device *device,
> @@ -236,7 +236,7 @@ static int acpi_video_get_brightness(struct backlight_device *bd)
>  	struct acpi_video_device *vd =
>  		(struct acpi_video_device *)bl_get_data(bd);
>  
> -	if (acpi_video_device_lcd_get_level_current(vd, &cur_level, 0))
> +	if (acpi_video_device_lcd_get_level_current(vd, &cur_level, false))
>  		return -EINVAL;
>  	for (i = 2; i < vd->brightness->count; i++) {
>  		if (vd->brightness->levels[i] == cur_level)
> @@ -281,7 +281,7 @@ static int video_get_cur_state(struct thermal_cooling_device *cooling_dev, unsig
>  	unsigned long long level;
>  	int offset;
>  
> -	if (acpi_video_device_lcd_get_level_current(video, &level, 0))
> +	if (acpi_video_device_lcd_get_level_current(video, &level, false))
>  		return -EINVAL;
>  	for (offset = 2; offset < video->brightness->count; offset++)
>  		if (level == video->brightness->levels[offset]) {
> @@ -452,7 +452,7 @@ static struct dmi_system_id video_dmi_table[] __initdata = {
>  
>  static int
>  acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
> -					unsigned long long *level, int init)
> +					unsigned long long *level, bool raw)
>  {
>  	acpi_status status = AE_OK;
>  	int i;
> @@ -463,6 +463,15 @@ acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
>  		status = acpi_evaluate_integer(device->dev->handle, buf,
>  						NULL, level);
>  		if (ACPI_SUCCESS(status)) {
> +			if (raw) {
> +				/*
> +				 * Caller has indicated he wants the raw
> +				 * value returned by _BQC, so don't furtherly
> +				 * mess with the value.
> +				 */
> +				return 0;
> +			}
> +
>  			if (device->brightness->flags._BQC_use_index) {
>  				if (device->brightness->flags._BCL_reversed)
>  					*level = device->brightness->count
> @@ -476,16 +485,14 @@ acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
>  					device->brightness->curr = *level;
>  					return 0;
>  			}
> -			if (!init) {
> -				/*
> -				 * BQC returned an invalid level.
> -				 * Stop using it.
> -				 */
> -				ACPI_WARNING((AE_INFO,
> -					      "%s returned an invalid level",
> -					      buf));
> -				device->cap._BQC = device->cap._BCQ = 0;
> -			}
> +			/*
> +			 * BQC returned an invalid level.
> +			 * Stop using it.
> +			 */
> +			ACPI_WARNING((AE_INFO,
> +				      "%s returned an invalid level",
> +				      buf));
> +			device->cap._BQC = device->cap._BCQ = 0;
>  		} else {
>  			/* Fixme:
>  			 * should we return an error or ignore this failure?
> @@ -703,7 +710,8 @@ acpi_video_init_brightness(struct acpi_video_device *device)
>  	if (!device->cap._BQC)
>  		goto set_level;
>  
> -	result = acpi_video_device_lcd_get_level_current(device, &level_old, 1);
> +	result = acpi_video_device_lcd_get_level_current(device,
> +							 &level_old, true);
>  	if (result)
>  		goto out_free_levels;
>  
> @@ -714,7 +722,7 @@ acpi_video_init_brightness(struct acpi_video_device *device)
>  	if (result)
>  		goto out_free_levels;
>  
> -	result = acpi_video_device_lcd_get_level_current(device, &level, 0);
> +	result = acpi_video_device_lcd_get_level_current(device, &level, true);
>  	if (result)
>  		goto out_free_levels;
>  
> @@ -1268,7 +1276,8 @@ acpi_video_switch_brightness(struct acpi_video_device *device, int event)
>  		goto out;
>  
>  	result = acpi_video_device_lcd_get_level_current(device,
> -							 &level_current, 0);
> +							 &level_current,
> +							 false);
>  	if (result)
>  		goto out;
>  
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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