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Commit f70ac0e9 authored by Danny Kukawka's avatar Danny Kukawka Committed by Len Brown
Browse files

ACPI video: Don't export sysfs backlight interface if query _BCL fail 

Currently the acpi video module export the backlight interface to sysfs
also if acpi_video_device_lcd_query_levels() fails to read _BLC method
(e.g.  because the method is not available).  In this case the userspace
don't know which brightness level are supported and can't set a brightness
level (echo return with: "write error: Invalid Argument").  This happend
e.g.  on a ASUS RF1 (correct supported by the asus-laptop module).

The video module should not export the backlight interface if query _BLC fail,
because you can't set anything from userspace and this make it useless.

http://bugzilla.kernel.org/show_bug.cgi?id=8375



Signed-off-by: default avatarDanny Kukawka <dkukawka@suse.de>
Acked-by: default avatarLuming Yu <luming.yu@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 23b0f015

drivers/acpi/video.c

+42 −38
Original line number Diff line number Diff line
@@ -559,7 +559,6 @@ acpi_video_bus_DOS(struct acpi_video_bus *video, int bios_flag, int lcd_flag) 


static void acpi_video_device_find_cap(struct acpi_video_device *device)

{

	acpi_integer status;

	acpi_handle h_dummy1;

	int i;

	u32 max_level = 0;
@@ -593,9 +592,9 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device) 
		device->cap._DSS = 1;

	}



	status = acpi_video_device_lcd_query_levels(device, &obj);

	if (ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device, &obj))) {



	if (obj && obj->type == ACPI_TYPE_PACKAGE && obj->package.count >= 2) {

		if (obj->package.count >= 2) {

			int count = 0;

			union acpi_object *o;
@@ -616,6 +615,7 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device) 
						continue;

					}

					br->levels[count] = (u32) o->integer.value;



					if (br->levels[count] > max_level)

						max_level = br->levels[count];

					count++;
@@ -634,9 +634,13 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device) 
			}

		}



	} else {

		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available LCD brightness level\n"));

	}



	kfree(obj);



	if (device->cap._BCL && device->cap._BCM && device->cap._BQC){

	if (device->cap._BCL && device->cap._BCM && device->cap._BQC && max_level > 0){

		unsigned long tmp;

		static int count = 0;

		char *name;