thinkpad x1 carbon display flickering after update to 5.12. good on 5.11.x (i915)

[Thomas Stein]

Yes, it does indeed! No flicker anymore. Thanks and cheers!

On 2021-05-14 14:34, Oleksandr Natalenko wrote:
> Hello.
> 
> On Fri, May 14, 2021 at 10:24:26AM +0200, Thomas Stein wrote:
>> After upgrading to linux 5.12 the display on my X1 Carbon Gen 2 starts 
>> to
>> flicker. Well actually it seems to turn off and on again and again. 
>> Here a
>> link to a video a person posted who has the same issue as me 
>> obviousely. 
>> https://linuxove.com/thinkpad-x1-carbon-gen-3-display-flickering-on-linux-kernel-5-12/
>> 
>> This happens without having Xorg running too. So it can't be related 
>> to
>> Xorg. The kernel boots and after a few seconds, the kernel messages 
>> scoll
>> through, the flickering starts. Nothing special in dmesg.
>> 
>> dmesg:
>> 
>> himbeere at rather ~ $ dmesg | grep i915
>> [    0.713595] i915 0000:00:02.0: vgaarb: deactivate vga console
>> [    0.720280] i915 0000:00:02.0: vgaarb: changed VGA decodes:
>> olddecodes=io+mem,decodes=io+mem:owns=io+mem
>> [    0.741494] i915 0000:00:02.0: [drm] Panel advertises DPCD 
>> backlight
>> support, but VBT disagrees. If your backlight controls don't work try
>> booting with i915.enable_dpcd_backlight=1. If your machine needs this,
>> please file a _new_ bug report on drm/i915, see
>> https://gitlab.freedesktop.org/drm/intel/-/wikis/How-to-file-i915-bugs 
>> for
>> details.
>> [    1.864837] [drm] Initialized i915 1.6.0 20201103 for 0000:00:02.0 
>> on
>> minor 0
>> [    1.875907] fbcon: i915drmfb (fb0) is primary device
>> [    3.158255] i915 0000:00:02.0: [drm] fb0: i915drmfb frame buffer 
>> device
>> himbeere at rather ~ $
>> 
>> Downgrading to 5.11 solves the issue for me. Any ideas?
> 
> Does [1] fix your issue?
> 
> [1] 
> https://cgit.freedesktop.org/drm-tip/patch/?id=acca7762eb71bc05a8f28d29320d193150051f79