ACPI video: Don't export sysfs backlight interface if query _BCL fail (f70ac0e9) · Commits · 戴 / test

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:

Danny Kukawka <dkukawka@suse.de> Acked-by:

Luming Yu <luming.yu@intel.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Len Brown <len.brown@intel.com>

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;

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