[Update][PATCH] ACPI / video / i915: Remove ACPI backlight if firmware expects Windows 8

[Matthew Garrett]

On Tue, 2013-07-16 at 17:32 +0400, Igor Gnatenko wrote:
> Hmm. I found regression in user-space. In GNOME (maybe and other DEs) we no longer see switch status of backlight.

Yeah, I can duplicate that. Rafael, we have to call
acpi_video_init_brightness() even if we're not going to initialise the
backlight - Thinkpads seem to use this as the trigger for enabling ACPI
notifications rather than handling it in firmware. This seems to do the
job:

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 01b1a25..71865f7 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -900,6 +900,9 @@ static void acpi_video_device_find_cap(struct
acpi_video_device *device)
 		device->cap._DDC = 1;
 	}
 
+	if (acpi_video_init_brightness(device))
+		return;
+
 	if (acpi_video_verify_backlight_support()) {
 		struct backlight_properties props;
 		struct pci_dev *pdev;
@@ -909,9 +912,6 @@ static void acpi_video_device_find_cap(struct
acpi_video_device *device)
 		static int count = 0;
 		char *name;
 
-		result = acpi_video_init_brightness(device);
-		if (result)
-			return;
 		name = kasprintf(GFP_KERNEL, "acpi_video%d", count);
 		if (!name)
 			return;


-- 
Matthew Garrett | mjg59 at srcf.ucam.org