Commit d32f6947 authored by Zhang Rui's avatar Zhang Rui Committed by Len Brown
Browse files

ACPI video: support _BCL packages that don't export brightness levels when machine is on AC/Battery 

Many buggy BIOSes don't export the brightness levels when machine
is on AC/Battery in the _BCL method.

Reformat the _BCL package for these laptops:
now the elements in device->brightness->levels[] are like:
levels[0]: brightness level when on AC power.
levels[1]: brightness level when on Battery power.
levels[2]: supported brightness level 1.
levels[3]: supported brightness level 2.
...
levels[n]: supported brightness level n-1.
levels[n + 1]: supported brightness level n.
So if there are n supported brightness levels on this laptop,
we will have n+2 entries in device->brightnes->levels[].

level[0] and level[1] are invalid on the laptops that don't
export the brightness levels on AC/Battery.
Fortunately, we never use these two values at all, even for the
valid ones.

http://bugzilla.kernel.org/show_bug.cgi?id=12249



Signed-off-by: default avatarZhang Rui <rui.zhang@intel.com>
Acked-by: default avatarMatthew Garrett <mjg59@srcf.ucam.org>
Acked-by: default avatarThomas Renninger <trenn@suse.de>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 24450c7a

drivers/acpi/video.c

+30 −7
Original line number Diff line number Diff line
@@ -168,10 +168,15 @@ struct acpi_video_device_cap { 
	u8 _DSS:1;		/*Device state set */

};



struct acpi_video_brightness_flags {

	u8 _BCL_no_ac_battery_levels:1;	/* no AC/Battery levels in _BCL */

};



struct acpi_video_device_brightness {

	int curr;

	int count;

	int *levels;

	struct acpi_video_brightness_flags flags;

};



struct acpi_video_device {
@@ -682,7 +687,7 @@ static int 
acpi_video_init_brightness(struct acpi_video_device *device)

{

	union acpi_object *obj = NULL;

	int i, max_level = 0, count = 0;

	int i, max_level = 0, count = 0, level_ac_battery = 0;

	union acpi_object *o;

	struct acpi_video_device_brightness *br = NULL;
@@ -701,7 +706,7 @@ acpi_video_init_brightness(struct acpi_video_device *device) 
		goto out;

	}



	br->levels = kmalloc(obj->package.count * sizeof *(br->levels),

	br->levels = kmalloc((obj->package.count + 2) * sizeof *(br->levels),

				GFP_KERNEL);

	if (!br->levels)

		goto out_free;
@@ -719,16 +724,34 @@ acpi_video_init_brightness(struct acpi_video_device *device) 
		count++;

	}



	/* don't sort the first two brightness levels */

	/*

	 * some buggy BIOS don't export the levels

	 * when machine is on AC/Battery in _BCL package.

	 * In this case, the first two elements in _BCL packages

	 * are also supported brightness levels that OS should take care of.

	 */

	for (i = 2; i < count; i++)

		if (br->levels[i] == br->levels[0] ||

		    br->levels[i] == br->levels[1])

			level_ac_battery++;



	if (level_ac_battery < 2) {

		level_ac_battery = 2 - level_ac_battery;

		br->flags._BCL_no_ac_battery_levels = 1;

		for (i = (count - 1 + level_ac_battery); i >= 2; i--)

			br->levels[i] = br->levels[i - level_ac_battery];

		count += level_ac_battery;

	} else if (level_ac_battery > 2)

		ACPI_ERROR((AE_INFO, "Too many duplicates in _BCL package\n"));



	/* sort all the supported brightness levels */

	sort(&br->levels[2], count - 2, sizeof(br->levels[2]),

		acpi_video_cmp_level, NULL);



	if (count < 2)

		goto out_free_levels;



	br->count = count;

	device->brightness = br;

	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "found %d brightness levels\n", count));

	ACPI_DEBUG_PRINT((ACPI_DB_INFO,

			  "found %d brightness levels\n", count - 2));

	kfree(obj);

	return max_level;

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