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

Matthew Garrett
2013-07-16T17:08:16Z

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@srcf.ucam.org