Commit c504f8cb authored by Zhang Rui's avatar Zhang Rui Committed by Len Brown
Browse files

ACPI video: Prune dupe video devices, unless "video.allow_duplicates" 

Some buggy BIOS exports multiple ACPI video bus devices for the same
VGA controller, and multiple backlight control methods as well.
This messes up the ACPI video backlight control.

http://bugzilla.kernel.org/show_bug.cgi?id=13577



With this patch applied, only the FIRST ACPI video bus device
under a PCI device node is bind to ACPI video driver by default.

If the first ACPI video bus device doesn't work well, we can use
video.allow_duplicates=1 to go back to the old behavior.

Signed-off-by: default avatarZhang Rui <rui.zhang@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 6b7b2849

drivers/acpi/video.c

+43 −0
Original line number Diff line number Diff line
@@ -78,6 +78,13 @@ MODULE_LICENSE("GPL"); 
static int brightness_switch_enabled = 1;

module_param(brightness_switch_enabled, bool, 0644);



/*

 * By default, we don't allow duplicate ACPI video bus devices

 * under the same VGA controller

 */

static int allow_duplicates;

module_param(allow_duplicates, bool, 0644);



static int register_count = 0;

static int acpi_video_bus_add(struct acpi_device *device);

static int acpi_video_bus_remove(struct acpi_device *device, int type);
@@ -2233,11 +2240,47 @@ static int acpi_video_resume(struct acpi_device *device) 
	return AE_OK;

}



static acpi_status

acpi_video_bus_match(acpi_handle handle, u32 level, void *context,

			void **return_value)

{

	struct acpi_device *device = context;

	struct acpi_device *sibling;

	int result;



	if (handle == device->handle)

		return AE_CTRL_TERMINATE;



	result = acpi_bus_get_device(handle, &sibling);

	if (result)

		return AE_OK;



	if (!strcmp(acpi_device_name(sibling), ACPI_VIDEO_BUS_NAME))

			return AE_ALREADY_EXISTS;



	return AE_OK;

}



static int acpi_video_bus_add(struct acpi_device *device)

{

	struct acpi_video_bus *video;

	struct input_dev *input;

	int error;

	acpi_status status;



	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,

				device->parent->handle, 1,

				acpi_video_bus_match, NULL,

				device, NULL);

	if (status == AE_ALREADY_EXISTS) {

		printk(KERN_WARNING FW_BUG

			"Duplicate ACPI video bus devices for the"

			" same VGA controller, please try module "

			"parameter \"video.allow_duplicates=1\""

			"if the current driver doesn't work.\n");

		if (!allow_duplicates)

			return -ENODEV;

	}



	video = kzalloc(sizeof(struct acpi_video_bus), GFP_KERNEL);

	if (!video)

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