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

[Rafael J. Wysocki]

On Wednesday, July 17, 2013 09:16:38 AM Igor Gnatenko wrote:
> On Wed, 2013-07-17 at 00:01 +0200, Rafael J. Wysocki wrote:
> > On Tuesday, July 16, 2013 05:08:16 PM Matthew Garrett wrote:
> > > 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:
> > 
> > Igor, does this additional patch from Matthew help?
> Yes. With this patch I have backlight switch indicator on my ThinkPad X230.

OK, thanks for the confirmation.

Can you please also check if applying the appended patch on top of the Matthew's
one changes anything (ie. things still work)?

Rafael


---
 drivers/acpi/video.c |    5 +++++
 1 file changed, 5 insertions(+)

Index: linux-pm/drivers/acpi/video.c
===================================================================
--- linux-pm.orig/drivers/acpi/video.c
+++ linux-pm/drivers/acpi/video.c
@@ -957,6 +957,11 @@ static void acpi_video_device_find_cap(s
 		if (result)
 			printk(KERN_ERR PREFIX "Create sysfs link\n");
 
+	} else {
+		/* Remove the brightness object. */
+		kfree(device->brightness->levels);
+		kfree(device->brightness);
+		device->brightness = NULL;
 	}
 }