Bug 19313 - [915GM UXA] readpix incorrect displayed
Summary: [915GM UXA] readpix incorrect displayed
Alias: None
Product: Mesa
Classification: Unclassified
Component: Drivers/DRI/i915 (show other bugs)
Version: unspecified
Hardware: Other Linux (All)
: high normal
Assignee: Eric Anholt
QA Contact:
Depends on:
Blocks: 18841
  Show dependency treegraph
Reported: 2008-12-28 19:13 UTC by zhao jian
Modified: 2009-01-06 22:46 UTC (History)
3 users (show)

See Also:
i915 platform:
i915 features:

xorg.conf (3.36 KB, text/plain)
2008-12-28 19:13 UTC, zhao jian
xorg.0.log (41.44 KB, text/plain)
2008-12-28 19:14 UTC, zhao jian
readpix_uxa (142.06 KB, image/x-png)
2008-12-28 19:15 UTC, zhao jian

Description zhao jian 2008-12-28 19:13:34 UTC
Created attachment 21528 [details]

System Environment:
Host:          915gm
Arch:          i386
OSD:            Fedora release 8 (Werewolf)
Kernel:        2.6.28 release 
Libdrm:		(master)  c34539e8bb5568b1d6059abf139dd08e07e84eea
Mesa:		(intel-2008-q4) 88f4b17555be36f3023f74a1b9c792294f09912b
Xorg:		7.2
Xserver:	(server-1.6-branch) 32e81074b967716865aef08b66ec29caf0fec2c5
Xf86_video_intel_stable:		(xf86-video-intel-2.6-branch)892cb5db6fd4c5cc692bc74a2615860f27e9feff

Bug Description:
Run readpix, and the read/write will have a incorrect display. As shown in attachment. 

Reproduce steps:
1.enable UXA
3.run demo/readpix
Comment 1 zhao jian 2008-12-28 19:14:30 UTC
Created attachment 21529 [details]
Comment 2 zhao jian 2008-12-28 19:15:04 UTC
Created attachment 21530 [details]
Comment 3 zhao jian 2008-12-28 23:04:02 UTC
I tried to run it with option tiling off, but it still incorrect. 
In EXA, it is OK both with this option on and off. 
Comment 4 Gordon Jin 2008-12-29 00:17:24 UTC
Maybe what Kui got on his EeePC901 with Moblin build is related with this issue.
Comment 5 Eric Anholt 2009-01-06 11:24:22 UTC
commit 9a5082d2920c1a212fe935b5a093013e8035c321
Author: Eric Anholt <eric@anholt.net>
Date:   Mon Jan 5 23:28:50 2009 -0800

    Disable DRI2 buffer tiling on non-965, as those need fence regs for 2D blits
    This fixes glReadPixels failure on single-channel 915GM, as the software cod
    for readpixels was actually the only code in the driver doing tiling against
    these buffers (everything else says "rely on fence registers", since the 2D
    blits don't have a "don't rely on fence registers" option).
Comment 6 zhao jian 2009-01-06 22:46:02 UTC
It now works well. I tested it on 915gm with following configuration:

Host:          915gm
Arch:          i386
OSD:            Fedora release 8 (Werewolf)
Kernel:        2.6.28 release 
Libdrm:          (master)c34539e8bb5568b1d6059abf139dd08e07e84eea
Mesa:            (intel-2008-q4)b9921a9fb2bc937194eac7e80e31d30f81cb6bb1
Xorg:            7.2
Xserver:         (server-1.6-branch)32e81074b967716865aef08b66ec29caf0fec2c5

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