Only one ACPI video bus device for a VGA controller. 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. The questions is that, we never notice this kind of devices before, thus I'm not sure this won't break any laptops. I suggest we put this patch in ACPI test tree first. Tested-by: Hector Martin <hector@xxxxxxxxxxxxxx> Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx> --- drivers/acpi/video.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) Index: linux-2.6/drivers/acpi/video.c =================================================================== --- linux-2.6.orig/drivers/acpi/video.c +++ linux-2.6/drivers/acpi/video.c @@ -2195,11 +2195,43 @@ static int acpi_video_resume(struct acpi 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; + + /* only one ACPI bus video device under a PCI device */ + 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, device, NULL); + if (status == AE_ALREADY_EXISTS) { + printk(KERN_WARNING PREFIX, "Duplicate ACPI video bus " + "devices for the same VGA controller\n"); + return -ENODEV; + } video = kzalloc(sizeof(struct acpi_video_bus), GFP_KERNEL); if (!video) -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
