After updating from linux 3.12.8 to 3.13 my display backlight
switches off when starting X.
The kernel doesn't crash, it just switched off the backlight.
Hardware name: Acer Aspire 3820T/JM31_CP, BIOS V1.19 10/27/2010
This is a notebook with an intel/radeon hybrid graphics.
I use intel for my X. I report this as radeon problem because
git bisect (on linux-stable tree) showed the following commit
as the cause of my problem:
10ebc0bc09344ab6310309169efc73dfe6c23d72 is the first bad commit
Author: Dave Airlie <airlied at redhat.com>
Date: Mon Sep 17 14:40:31 2012 +1000
drm/radeon: add runtime PM support (v2)
This hooks radeon up to the runtime PM system to enable
dynamic power management for secondary GPUs in switchable
and powerxpress laptops.
v2: agd5f: clean up, add module parameter
Signed-off-by: Dave Airlie <airlied at redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Please let me know if you need addititonal information.
I have the same problem with radeon/intel laptop:
00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 18)
02:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Madison [Mobility Radeon HD 5650/5750 / 6530M/6550M] (rev ff)
As the problem still exists and prevents me from using any kernel 3.13+
I changed the priority of this bug.
When I did the git bisect I hoped it would help to find a solution soon.
Is there anything I can do to help fixing this problem?
I don't want to get stuck on kernel 3.12.20 :(
Does disabling runpm help? Boot with radeon.runpm=0 on the kernel command line in grub.
(In reply to comment #3)
> Does disabling runpm help? Boot with radeon.runpm=0 on the kernel command
> line in grub.
yes it does :)
Please attach your dmesg output. Is this a muxed or muxless laptop?
Created attachment 99349 [details] [review]
Does the attached patch help?
Created attachment 99424 [details]
dmesg output before patching (and with runpm)
(In reply to comment #7)
> Does the attached patch help?
The patch works fine, however the display backlight switches off for several seconds during X init now (it didn't with kernel 2.12) but this is not really a problem, as it comes back happily :) thank you.
Created attachment 99427 [details] [review]
possible fix v2
(In reply to comment #9)
> The patch works fine, however the display backlight switches off for several
> seconds during X init now (it didn't with kernel 2.12) but this is not
> really a problem, as it comes back happily :) thank you.
Does this patch work any better?
(In reply to comment #10)
> Created attachment 99427 [details] [review] [review]
> possible fix v2
> Does this patch work any better?
No, pretty much the same behaviour as the first version here. The backlight switches off when X starts, and comes backs ~5 seconds later. (same delay in restoring backlight after resume from suspend)
I am affected by this bug too.
I have a Acer 3820TG laptop featuring Intel IGP (Ironlake) / AMD DGP (Radeon 6550M). It kept me stucked with kernel 3.12 series until I googled for "backlight issue" rather than "Intel driver issue" and found THIS bug report. :-)
adding radeon.runpm=0 to the boot options works for me too. I haven't tested the patch yet.
FWIW, I'd like to add 2 side informations hoping it might be related :
- the backlight control only works for the Intel IGP. If the laptop goes idle when on the radeon, waking it up doesn't bring the backlight back.
- when switching from Ironlake to Radeon through VGA switcheroo, I have to use "ON -> MIGD -> DDIS" sequence as the screen goes black immediately after passing "ON".
Forgot to say : this is a muxed laptop.
Fix is upstream:
and will make it's way back to stable kernels as well.
I just applied the fixed against 3.15.0, and it does work as reported.
The 5s delay at X startup is a bit annoying but acceptable...
In my case it actually happens twice :
- at X startup
- at session start (presumably when the XFCE power manager tool starts up)
Thank you for helping us out