Bug 105465

Summary: Computer boots into black screen when MST is used
Product: DRI Reporter: kartongsaft <johan.bjornehall>
Component: DRM/IntelAssignee: Dhinakaran Pandiyan <dhinakaran.pandiyan>
Status: CLOSED FIXED QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: major    
Priority: high CC: intel-gfx-bugs, jani.nikula, johan.bjornehall, joonas.lahtinen
Version: unspecified   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
See Also: https://bugs.freedesktop.org/show_bug.cgi?id=105470
Whiteboard: ReadyForDev
i915 platform: SKL i915 features: display/DP MST
Attachments:
Description Flags
dmesg
none
fkFfWrn - Imgur.mp4
none
s3muMLI - Imgur.mp4
none
kqiWPsM - Imgur.jpg none

Description kartongsaft 2018-03-12 19:38:01 UTC
On kernel 4.15.8 (and a way back), computer boots into black screen every time with multiple monitors connected with a single DisplayPort cable. Intel i3-6100 (Skylake) with Intel HD Graphics 530.

If MST is disabled in GRUB with i915.enable_dp_mst=0, the issue goes away but leaves me with mirrored screens.

This issue occurred somewhere in november 2017, but I didn't file a bug report because of the belief of misconfiguration.

More information about the symptom for the issue, can be obtained here. https://bbs.archlinux.org/viewtopic.php?id=233138
Comment 1 kartongsaft 2018-03-12 19:58:58 UTC
Created attachment 138039 [details]
dmesg
Comment 2 kartongsaft 2018-03-12 20:14:44 UTC
Created attachment 138040 [details]
fkFfWrn - Imgur.mp4
Comment 3 kartongsaft 2018-03-12 20:15:13 UTC
Created attachment 138041 [details]
s3muMLI - Imgur.mp4
Comment 4 kartongsaft 2018-03-12 20:22:18 UTC
Created attachment 138042 [details]
kqiWPsM - Imgur.jpg
Comment 5 kartongsaft 2018-03-12 20:27:13 UTC
I just wanna add that when my screens are black, I am able to type in my logon credentials and start Xorg (see attachment kqiWPsM - Imgur.jpg).
Comment 6 kartongsaft 2018-03-13 21:08:40 UTC
The monitors I'm using are Dell U2515H.
Comment 7 Dhinakaran Pandiyan 2018-03-14 18:29:52 UTC
Can you please check if this patch fixes the issue https://patchwork.freedesktop.org/patch/210500/ ?
Comment 8 kartongsaft 2018-03-14 19:30:52 UTC
(In reply to Dhinakaran Pandiyan from comment #7)
> Can you please check if this patch fixes the issue
> https://patchwork.freedesktop.org/patch/210500/ ?

How do I apply the patch and redo the changes if something goes wrong?
Comment 9 kartongsaft 2018-03-15 22:11:24 UTC
I downloaded the source for 4.15.8, but where unable to patch because of mismatch. Idea how to proceed?
Comment 10 Elizabeth 2018-03-16 17:58:23 UTC
I'm not sure if that patch was meant to work over drm-tip https://cgit.freedesktop.org/drm-tip, maybe?
Comment 11 kartongsaft 2018-03-17 18:13:19 UTC
(In reply to Elizabeth from comment #10)
> I'm not sure if that patch was meant to work over drm-tip
> https://cgit.freedesktop.org/drm-tip, maybe?

Should I apply drm-tip to my system or what?
Comment 12 frederik 2018-03-18 16:27:39 UTC
I tried this patch (for a different report) on top of mainline and it works fine.
Comment 13 kartongsaft 2018-03-18 18:04:12 UTC
(In reply to frederik from comment #12)
> I tried this patch (for a different report) on top of mainline and it works
> fine.

Does this mean that the patch is gonna be merged and be available through stable?
Comment 14 Dhinakaran Pandiyan 2018-03-19 19:16:34 UTC
It should become available in the stable kernel, not sure when exactly though.
Comment 15 Dhinakaran Pandiyan 2018-03-19 19:19:01 UTC
Patch merged to drm-tip.

commit ad260ab32a4d94fa974f58262f8000472d34fd5b
Author: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Date:   Tue Mar 13 22:48:25 2018 -0700

    drm/i915/dp: Write to SET_POWER dpcd to enable MST hub.
Comment 16 Jani Saarinen 2018-04-20 10:56:17 UTC
HI, reporter closing this, please re-open if you can reproduce using drm-tip.
Comment 17 kartongsaft 2018-04-22 16:36:57 UTC
(In reply to Jani Saarinen from comment #16)
> HI, reporter closing this, please re-open if you can reproduce using drm-tip.

I have re-opened the bug, as the issue is still there with 4.16.3.
Comment 18 Jani Saarinen 2018-04-23 06:28:43 UTC
Please test with drm-tip too.
https://cgit.freedesktop.org/drm-tip
Comment 19 kartongsaft 2018-04-30 15:34:48 UTC
(In reply to Jani Saarinen from comment #18)
> Please test with drm-tip too.
> https://cgit.freedesktop.org/drm-tip

As there isn't any easy way to test the latest drm-tip, can you identify in which version of the kernel this patch was merged? I'm currently running 4.16.5 and the issue is still there.
Comment 20 Jani Saarinen 2018-04-30 17:13:27 UTC
Jani, Joonas, can you help?
Comment 21 kartongsaft 2018-05-08 20:38:11 UTC
This is resolved in 4.16.7. Thanks!
Comment 22 Jani Saarinen 2018-05-09 05:24:52 UTC
Thanks, closing
Comment 23 Jani Nikula 2018-05-09 06:10:34 UTC
For posterity, the only commit that landed between v4.16.5 and v4.16.7 that seems to have any relevance here is the backport of upstream commit df9e6521749a ("drm/i915/fbdev: Enable late fbdev initial configuration").

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