Bug#832332: linux-image-4.6.0-1-amd64: Flickering X display for Intel HD 4600 (i915 driver)

[Bram Bolder <bb@fd0.org>]

Hello Vincent,

thanks for your reply.

On 07/24/2016 04:19 PM, Vincent Bernat wrote:
>  ❦ 24 juillet 2016 13:45 CEST, Bram Bolder <bb@fd0.org> :
>
> > after upgrading the meta package 'linux-image-amd64' from linux-image-4.5.0-2-amd64
> > to linux-image-4.6.0-1-amd64 (and rebooting), my laptop screen started to flicker
> > annoyingly. At first I thought it was a hardware defect (backlight lamp reaching
> > its end of life), but booting an Ubuntu or reverting to the 4.5.0-2 does not show
> > any flickering. The normal terminals (alt-F1 through alt-F6) do not flicker.
> >
> > My laptop has seen many generations of Linux images while using 'Debian testing',
> > all without problems, so it must be related to this latest kernel version.
> > I tried a clean installation of SID (i.e. without explicitly configuring xorg),
> > but it reproduces the flickering.
>
> Is /sys/module/i915/parameters/enable_psr set to 1? If yes, can you try
> to set it to 0 and check if the problem goes away (no need to restart
> anything).

It was set to 1, changing it to 0 did not solve the problem (I stopped xdm,
set the 0 and started it again).

I did some further checking (kernel 4.5 has enable_psr=0 as default). I also
noticed that producing load removed the flickering (e.g. glxgears). It's definitively
a power saving feature.

I then tried to set i915.enable_psr=0 as commandline option in grub and this solved
my problem! Hooray!


My question now is how to proceed with this problem. I'm quite sure that you don't want
everyone with my (or a similar) hardware setup to file a bugreport to you. Maybe this
problem gets fixes upstream at some point...

Do you want to close this ticket? The problem is solved for me, but maybe other users
might experience the same problem.


Thanks for your help,

Bram