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

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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: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Zhang Rui 2009-12-30 15:59:23 +08:00 committed by Len Brown
parent 6b7b284958
commit c504f8cb68
1 changed files with 43 additions and 0 deletions
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43
drivers/acpi/video.c
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@ -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)