Bug 79386

Created attachment 100045 [details]
flickering

Created attachment 100046 [details]
intel_reg_dumper output: 3600836585e3fdef0a1410d63fe5ce4015007aac

Created attachment 100047 [details]
intel_reg_dumper output: 4e53c2e010e531b4a014692199e978482d471c7e

Hi

Can you please boot your machine with "drm.debug=0xe" Kernel parameter, reproduce the bug, then attach the output of the  "dmesg" command here?

Thanks,
Paulo

Created attachment 100318 [details]
dmesg output: 3600836585e3fdef0a1410d63fe5ce4015007aac

i have this too.
did some youtube: https://www.youtube.com/watch?v=PLEw_pkaLks

what can i do to help with that (i am not that pro but i will try it).
things i have tried so fare:
works well with any kernel 3.8
problems starts with kernel 3.9
also latest 3.15 have this problem.
i also have asus timeline U M5 Laptop.

I guess it is a WM issue. Double check that Ville hasn't already fixed it in drm-intel-nightly and if it is still broken, please bisect where the breakage was introduced between 3.8 and 3.9.

I do not think its is purely a WM (I am assuming this means window manager) issue. As I have mentioned before, the flicker occurs whether X is started or not. It is true that there is dramatically less flickering when X is not started, but on kernels that work, there is no flickering in either case. This leads me to believe that if the flickering without a WM is eliminated, then the flickering with one will be as well, though obviously this it not certain.

As for bisection, I find that the problem occurs between 3.9 and 3.10 and not 3.8 and 3.9 as Thomas claims. I bisected it to be introduced by commit 3600836585e3fdef0a1410d63fe5ce4015007aac.

yes thats what you wrote in your first post.
is this so difficult to fix?
I realy think this is a show stopper! I cant use new kernels at all.

(In reply to comment #8)
> I do not think its is purely a WM (I am assuming this means window manager)
> issue.

WM == watermarks on the display fifo. If we set those incorrectly, the display is liable to flicker or show other corruption and possibly hang the machine.

so what can we do to get this bug resolved?
how can i check it is a watermarks bug?

(In reply to comment #11)
> so what can we do to get this bug resolved?
> how can i check it is a watermarks bug?

checked with http://kernel.ubuntu.com/~kernel-ppa/mainline/drm-intel-nightly/current/linux-image-3.17.0-994-generic_3.17.0-994.201408200253_amd64.deb

(In reply to comment #8)
> I do not think its is purely a WM (I am assuming this means window manager)
> issue. As I have mentioned before, the flicker occurs whether X is started
> or not. It is true that there is dramatically less flickering when X is not
> started, but on kernels that work, there is no flickering in either case.
> This leads me to believe that if the flickering without a WM is eliminated,
> then the flickering with one will be as well, though obviously this it not
> certain.
> 
> As for bisection, I find that the problem occurs between 3.9 and 3.10 and
> not 3.8 and 3.9 as Thomas claims. I bisected it to be introduced by commit
> 3600836585e3fdef0a1410d63fe5ce4015007aac.

well i cant use Kernel 3.9! it is only working for me with Kernel 3.8

Please try current upstream or drm-intel-nightly branch of [1] first. We're pretty far from 3.8 or 3.10 by now.

If that doesn't help, well, just a hunch, please try the patch from [2] on top.

[1] http://cgit.freedesktop.org/drm-intel

[2] https://bugs.freedesktop.org/show_bug.cgi?id=81647#c5

(In reply to comment #14)
> Please try current upstream or drm-intel-nightly branch of [1] first. We're
> pretty far from 3.8 or 3.10 by now.
> 
> If that doesn't help, well, just a hunch, please try the patch from [2] on
> top.
> 
> [1] http://cgit.freedesktop.org/drm-intel
> 
> [2] https://bugs.freedesktop.org/show_bug.cgi?id=81647#c5

The patch in [2] works. Thank you very much!

commit 39fde1cdcc5df26bd65a2b9b765ae5b741ca6d13
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Tue Sep 9 11:25:13 2014 +0300

    drm/i915/edp: use lane count and link rate from DPCD for eDP

*** Bug 81647 has been marked as a duplicate of this bug. ***

How can i Test if this works for me too with ubuntu 14.04 (or 14.10)?

Created attachment 108410 [details]
Patch to fix the flickering

Created attachment 108411 [details]
Arch linux PKGBUILD that builds a fixed kernel

(In reply to Thomas from comment #18)
> How can i Test if this works for me too with ubuntu 14.04 (or 14.10)?

You need to compile a custom kernel for ubuntu. I'm not really sure how to do that but you can probably do a google search. You need to apply the attached patch before you compile. There are probably some patches that ubuntu applies to the kernel as well, so its probably best to apply this patch before all of them in the script that builds the kernel.dpkg. You can refer to my modified archlinux pkgbuild for some guidance on how to apply the patch.

I've tested the patch against the official archlinux 3.17 kernel and it patches successfully, but its possible that the ubuntu patches may conflict with this patch. In that case, it's will be very difficult for someone without knowledge of C programming and the structure of this part of the kernel's code to resolve the issue. If memory serves me correctly, ubuntu also provide a vanilla kernel with minimal patches, so it may be better to try modify the build script for that.

Failing that you can post a bug against the ubuntu kernel package and ask them to include this patch in their release.