Bug 94514

Summary: 24bit-source-pictures don't sample alpha=0 outside surface bounds [glamor]
Product: xorg Reporter: Clemens Eisserer <linuxhippy>
Component: Server/Acceleration/glamorAssignee: Xorg Project Team <xorg-team>
Status: RESOLVED FIXED QA Contact: Xorg Project Team <xorg-team>
Severity: normal    
Priority: medium    
Version: unspecified   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:
Attachments:
Description Flags
glamor: Only force alpha to 1.0 inside source pictures
none
self-contained testcase none

Description Clemens Eisserer 2016-03-12 19:12:39 UTC 
Same behaviour mentioned in bug 16820 and bug 17933:

Composition with 24-bit source pixmaps does not result in alpha=0 outside source surface bounds, instead it samples as black a=255, rgb=0.

Tested on AMD Mullins running an updated instance of Fedora-23 (Xorg 1.18.1, radeon 7.6.99, Linux 4.4.4).
Comment 1 Michel Dänzer 2016-03-14 08:51:19 UTC 
What's your test case?
Comment 2 Michel Dänzer 2016-03-15 08:22:33 UTC 
Ideally, there'd be a rendercheck test case exercising this.

Meanwhile, this is more likely an issue in glamor or the Mesa radeonsi driver than in the Xorg driver. Reassigning to glamor for now. (Maybe you can try if it also happens with the modesetting driver using glamor on other hardware?)
Comment 3 Michel Dänzer 2016-03-15 08:44:52 UTC 
Created attachment 122306 [details] [review]
glamor: Only force alpha to 1.0 inside source pictures

Does this xserver patch fix the probem?
Comment 4 Clemens Eisserer 2016-05-16 12:25:21 UTC 
Created attachment 123778 [details]
self-contained testcase

Thanks a lot for looking into this issue. 

Unfortunatly I can't compile X on the machine where I saw this issue, so I decided to create a self-contained testcase.
Comment 5 Michel Dänzer 2016-05-24 09:16:43 UTC 
Comment on attachment 122306 [details] [review]
glamor: Only force alpha to 1.0 inside source pictures

https://patchwork.freedesktop.org/patch/88805/ fixes the attached test case for me.
Comment 6 Michel Dänzer 2016-05-26 08:33:27 UTC 
commit 4711ebc174206b5a50e6ae8a7f974cd835e4ebd3
Author: Michel Dänzer <michel.daenzer@amd.com>
Date:   Tue May 24 18:12:42 2016 +0900

    glamor: Fix sampling outside of RGBx source/mask pictures

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