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ACPI video: Fix brightness control initialization for some laptops.

PATCH In review Danny Baumann 3 participants 6 messages Mar 19, 2013 – Mar 26, 2013 ACPI

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Danny Baumann

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#0 lore raw

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

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 <[email protected]>
---
 drivers/acpi/video.c | 43 ++++++++++++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 17 deletions(-)
drivers/acpi/video.c +26 -17
index 313f959..09e4722 100644
@@ -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;
Signature · 1 line
1.8.1.4
author
#1 lore raw

PATCH v4 2/3 ACPI video: Make logic a little easier to understand.

Make code paths a little easier to follow, and don't needlessly continue list iteration.

Signed-off-by Danny Baumann <[email protected]>
---
 drivers/acpi/video.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)
drivers/acpi/video.c +7 -6
index 09e4722..89bf61e 100644
@@ -737,16 +737,17 @@ acpi_video_init_brightness(struct acpi_video_device *device)
 		 */
 		if (use_bios_initial_backlight) {
 			for (i = 2; i < br->count; i++)
-				if (level_old == br->levels[i])
+				if (level_old == br->levels[i]) {
 					level = level_old;
+					break;
+				}
 		}
-		goto set_level;
+	} else {
+		if (br->flags._BCL_reversed)
+			level_old = (br->count - 1) - level_old;
+		level = br->levels[level_old];
 	}
 
-	if (br->flags._BCL_reversed)
-		level_old = (br->count - 1) - level_old;
-	level = br->levels[level_old];
-
 set_level:
 	result = acpi_video_device_lcd_set_level(device, level);
 	if (result)
Signature · 1 line
1.8.1.4
author
#2 lore raw

PATCH v4 3/3 ACPI video: Fix applying indexed initial brightness value.

In reply to Danny Baumann

The value initially read via _BQC also needs to be offset by 2 to compensate for the first 2 special items in _BCL. Introduce a helper function that does the BQC-value-to-level conversion in order to not needlessly duplicate code.

Signed-off-by Danny Baumann <[email protected]>
---
 drivers/acpi/video.c | 60 ++++++++++++++++++++++++++++++++--------------------
 1 file changed, 37 insertions(+), 23 deletions(-)
drivers/acpi/video.c +37 -23
index 89bf61e..86beaa8 100644
@@ -450,6 +450,31 @@ static struct dmi_system_id video_dmi_table[] __initdata = {
 	{}
 };
 
+static unsigned long long
+acpi_video_bqc_value_to_level(struct acpi_video_device *device,
+			      unsigned long long bqc_value)
+{
+	unsigned long long level;
+
+	if (device->brightness->flags._BQC_use_index) {
+		/*
+		 * _BQC returns an index that doesn't account for
+		 * the first 2 items with special meaning, so we need
+		 * to compensate for that by offsetting ourselves
+		 */
+		if (device->brightness->flags._BCL_reversed)
+			bqc_value = device->brightness->count - 3 - bqc_value;
+
+		level = device->brightness->levels[bqc_value + 2];
+	} else {
+		level = bqc_value;
+	}
+
+	level += bqc_offset_aml_bug_workaround;
+
+	return level;
+}
+
 static int
 acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
 					unsigned long long *level, bool raw)

@@ -472,14 +497,8 @@ acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
 				return 0;
 			}
 
-			if (device->brightness->flags._BQC_use_index) {
-				if (device->brightness->flags._BCL_reversed)
-					*level = device->brightness->count
-								 - 3 - (*level);
-				*level = device->brightness->levels[*level + 2];
+			*level = acpi_video_bqc_value_to_level(device, *level);
 
-			}
-			*level += bqc_offset_aml_bug_workaround;
 			for (i = 2; i < device->brightness->count; i++)
 				if (device->brightness->levels[i] == *level) {
 					device->brightness->curr = *level;

@@ -728,24 +747,19 @@ acpi_video_init_brightness(struct acpi_video_device *device)
 
 	br->flags._BQC_use_index = (level == max_level ? 0 : 1);
 
-	if (!br->flags._BQC_use_index) {
+	if (use_bios_initial_backlight) {
+		level = acpi_video_bqc_value_to_level(device, level_old);
 		/*
-		 * Set the backlight to the initial state.
-		 * On some buggy laptops, _BQC returns an uninitialized value
-		 * when invoked for the first time, i.e. level_old is invalid.
-		 * set the backlight to max_level in this case
+		 * On some buggy laptops, _BQC returns an uninitialized
+		 * value when invoked for the first time, i.e.
+		 * level_old is invalid (no matter whether it's a level
+		 * or an index). Set the backlight to max_level in this case.
 		 */
-		if (use_bios_initial_backlight) {
-			for (i = 2; i < br->count; i++)
-				if (level_old == br->levels[i]) {
-					level = level_old;
-					break;
-				}
-		}
-	} else {
-		if (br->flags._BCL_reversed)
-			level_old = (br->count - 1) - level_old;
-		level = br->levels[level_old];
+		for (i = 2; i < br->count; i++)
+			if (level_old == br->levels[i])
+				break;
+		if (i == br->count)
+			level = max_level;
 	}
 
 set_level:
Signature · 1 line
1.8.1.4
author
#3 lore raw
In reply to Danny Baumann

v3 incorporates Aaron's feedback, v4 fixes my inability to use git send-email properly. Sorry for that.

Regards,

Danny

Am 19.03.2013 17:22, schrieb Danny Baumann:

Quoted 137 lines

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 <[email protected]>
---
  drivers/acpi/video.c | 43 ++++++++++++++++++++++++++-----------------
  1 file changed, 26 insertions(+), 17 deletions(-)
drivers/acpi/video.c +26 -17
index 313f959..09e4722 100644
@@ -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;
#4 lore raw
Quoted 2 lines · Danny Baumann

v3 incorporates Aaron's feedback, v4 fixes my inability to use git send-email properly. Sorry for that.

For the 3 patches, Reviewed-by: Aaron Lu <[email protected]>

BTW, you can put things like what has been changed in a new series in patch 0.

Thanks,
Aaron

Quoted 149 lines

Regards,

Danny

Am 19.03.2013 17:22, schrieb Danny Baumann:

Quoted 128 lines

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 <[email protected]>
---
  drivers/acpi/video.c | 43 ++++++++++++++++++++++++++-----------------
  1 file changed, 26 insertions(+), 17 deletions(-)
drivers/acpi/video.c +24 -16
index 313f959..09e4722 100644
@@ -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;

drivers/acpi/video.c acpi_video_switch_brightness(struct acpi_video_device *device, int event) · line 1283

Quoted 9 lines
drivers/acpi/video.c +2 -1
@@ -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;

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#5 lore raw
In reply to Danny Baumann
Quoted 18 lines · Danny Baumann

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.

Quoted 4 lines

Fix that by returning the raw value returned by the _BQC call in the initialization case.

Signed-off-by Danny Baumann <[email protected]>

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

Thanks,
Rafael

Quoted 115 lines
---
 drivers/acpi/video.c | 43 ++++++++++++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 17 deletions(-)
drivers/acpi/video.c +26 -17
index 313f959..09e4722 100644
@@ -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;
Signature · 2 lines
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.