Bug 101441

Summary: [GLK][BXT]Artifacts that follow the mouse cursor in dual screen setups
Product: DRI Reporter: Ander Conselvan de Oliveira <conselvan2>
Component: DRM/IntelAssignee: Mahesh Kumar <mahesh1.kumar>
Status: CLOSED FIXED QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: normal    
Priority: medium CC: bugs, conselvan2, intel-gfx-bugs, luis.botello.ortega, madhav.chauhan, mahesh1.kumar, matthew.d.roper, mika.kahola, rodrigo.vivi
Version: DRI git   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: BXT, GLK i915 features:
Attachments:
Description Flags
dmesg log: boot with eDP; HDMI hotplugged later
none
Don't fix cursor DDB none

Description Ander Conselvan de Oliveira 2017-06-15 08:17:34 UTC 
Created attachment 131969 [details]
dmesg log: boot with eDP; HDMI hotplugged later

Some dual screen setups are currently broken. All the scanlines below the mouse cursor are wrong, sometimes containing a shade of gray and others repeating the image above it. I've seen this in APL and GLK using DSI+HDMI, eDP+HDMI and DSI+DP. In the DP case, however, the screen goes blank and reports lack of signal.

git bisect points at 

commit bb9d85f6e9de8fef5236c076530eab67a2f2431b
Author: Kumar, Mahesh <mahesh1.kumar@intel.com>
Date:   Thu Jun 1 11:29:18 2017 +0530

    drm/i915/skl: New ddb allocation algorithm
Comment 1 Mahesh Kumar 2017-06-15 15:19:52 UTC 
Created attachment 131984 [details] [review]
Don't fix cursor DDB

Hi Ander,

As per our debugging, In new algorithm minimum WM requirement for Cursor plane is increasing & it's more than cursor allocated DDB (8-blocks).
Because of which Cursor WM are getting disabled in system.
I created one RFC patch for not hard-coding cursor DDB to 8 in multi-pipe scenario, instead select a value from a particular range. This way we avoid re computing complete pipe's WM in each cursor update as well.

Please let me know if it helps.
Comment 2 Elizabeth 2017-06-15 16:08:42 UTC 
Changing the status to NEEDINFO, once you provide more information, please change the tag to REOPEN. Thank you.
Comment 3 Mika Kahola 2017-06-16 07:34:11 UTC 
I tested the patch and it did fix the corrupted scanlines when moving the mouse around. My setup was APL with DSI+DP connected.
Comment 4 Ander Conselvan de Oliveira 2017-06-16 11:20:23 UTC 
I'm not sure what is the next step here. The revert was merged, so should this be closed?

In any case, the patch fixed the issue in my GLK with eDP+HDMI too, tested on top of a drm-tip prior to the revert.

We definitely need to improve the test coverage to test dual screen. This is a very serious regression that slipped through. It would be good to have an igt test that exercises different configurations with varying DDB requirements.
Comment 5 Elizabeth 2017-06-16 22:09:37 UTC 
(In reply to Ander Conselvan de Oliveira from comment #4)
> I'm not sure what is the next step here. The revert was merged, so should
> this be closed?
> 
> In any case, the patch fixed the issue in my GLK with eDP+HDMI too, tested
> on top of a drm-tip prior to the revert.
> 
> We definitely need to improve the test coverage to test dual screen. This is
> a very serious regression that slipped through. It would be good to have an
> igt test that exercises different configurations with varying DDB
> requirements.

Closing bug since is reported as fixed. If there is any new problem concerning this case, please change the tag to "REOPEN". Thank you.

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.