Kernel Bug Tracker – Bug 19342
ACPI video backlight control doesn't work -- need backlight manager
Last modified: 2011-07-30 06:47:27 UTC
the ACPI video backlight control doesn't work on some machines. i.e. the backlight control method is evaluated properly but the backlight is not actually changed.
For these machines, we need to control the backlight via other ways, like, platform driver, PCI legacy register, graphics native register, etc.
So I'm planning to re-write the backlight sysfs class device to a backlight manager. More than one backlight driver can register to this backlight manager, and provide different callbacks to change the backlight.
And we can switch to other drivers if ACPI video driver doesn't work.
Even more, we can setup a blacklist for the laptops that known broken.
In a word, this bug report is a gathering of all the bugs that ACPI backlight control is broken and we don't/can't fix in Linux/kernel.
*** Bug 15513 has been marked as a duplicate of this bug. ***
*** Bug 14216 has been marked as a duplicate of this bug. ***
Have you looked at these patches?
No, I only saw the first patch before.
This is exactly what I want to do, and thanks for pointing it out. Jonathan,:)
what's the status of these patches?
I am the reporter for the Bug:15513. I can confirm controlling the brightness work with PPA kernel
But I need supply acpi_backlight=vendor
*** Bug 15528 has been marked as a duplicate of this bug. ***
workaround is available here:
It would be great if I can add "Tested-by:" before pushing these patches upstream.
Did the patches go in? I just had a go with Kubuntu 11.04 and back-light is still non-functional.
shipped in 2.6.39
Author: Matthew Garrett <firstname.lastname@example.org>
Date: Tue Mar 22 16:30:21 2011 -0700
backlight: add backlight type
There may be multiple ways of controlling the backlight on a given
machine. Allow drivers to expose the type of interface they are
providing, making it possible for userspace to make appropriate policy
Signed-off-by: Matthew Garrett <email@example.com>
Cc: Richard Purdie <firstname.lastname@example.org>
Cc: Chris Wilson <email@example.com>
Cc: David Airlie <firstname.lastname@example.org>
Cc: Alex Deucher <email@example.com>
Cc: Ben Skeggs <firstname.lastname@example.org>
Cc: Zhang Rui <email@example.com>
Cc: Len Brown <firstname.lastname@example.org>
Cc: Jesse Barnes <email@example.com>
Signed-off-by: Andrew Morton <firstname.lastname@example.org>
Signed-off-by: Linus Torvalds <email@example.com>