Bug 59150

Summary: [HSW Bisected]Piglit spec/ARB_vertex_type_2_10_10_10_rev/draw-vertices-2101010 fails
Product: Mesa Reporter: lu hua <huax.lu>
Component: Drivers/DRI/i965Assignee: Kenneth Graunke <kenneth>
Status: RESOLVED FIXED QA Contact: Intel 3D Bugs Mailing List <intel-3d-bugs>
Severity: normal    
Priority: medium CC: christophe.prigent, idr, xunx.fang
Version: unspecified   
Hardware: All   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:

Description lu hua 2013-01-09 02:49:06 UTC 
System Environment:
--------------------------
Arch:           x86_64
Platform:       Haswell
Libdrm:		(master)libdrm-2.4.40-6-g891517f5111cd82909906d5e8ee0299db0d46762
Mesa:		(master)a60c567fcf29f5d2a41222a8826fee2cb0eb4458
Xserver:	(master)xorg-server-1.13.99.901
Xf86_video_intel:(master)2.20.17-57-g8881a14200580db731ca6902b289b08989aaa61e
Cairo:		(master)5f2e89660d5e38d8e2682945962521958f150825
Libva:		(staging)2e11d2273b2974a7d1959cbcaf8db5b8e9aedd9e
Libva_intel_driver:(staging)066c9f6532b11e1e3d0457520dea565cd29faea7
Kernel:	(drm-intel-nightly) 52d697693f8e5bebd9c469dff214f608438bd6b8

Bug detailed description:
-------------------------
It fails on haswell with mesa master branch. Works well on ivybridge.

Bisect shows:a60c567fcf29f5d2a41222a8826fee2cb0eb4458 is the first bad commit.
commit a60c567fcf29f5d2a41222a8826fee2cb0eb4458
Author:     Kenneth Graunke <kenneth@whitecape.org>
AuthorDate: Fri Jan 4 07:53:12 2013 -0800
Commit:     Kenneth Graunke <kenneth@whitecape.org>
CommitDate: Mon Jan 7 16:48:02 2013 -0800

    i965: Support GL_FIXED and packed vertex formats natively on Haswell+.

    Haswell and later support the GL_FIXED and 2_10_10_10_rev vertex formats
    natively, and don't need shader workarounds.

    Reviewed-by: Eric Anholt <eric@anholt.net>

output:
Int vertices - 2/10/10/10
Unsigned Int vertices - 2/10/10/10
Int Color - 2/10/10/10
Probe at (45,5)
  Expected: 1.000000 0.000000 0.000000 0.333000
  Observed: 1.000000 0.000000 0.000000 0.000000
Unsigned Int Color - 2/10/10/10
Int BGRA Color - 2/10/10/10
Probe at (85,5)
  Expected: 0.000000 0.000000 1.000000 0.333000
  Observed: 0.000000 0.000000 1.000000 0.000000
Unsigned Int BGRA Color - 2/10/10/10
Int 2/10/10/10 - test ABI
Unsigned 2/10/10/10 - test ABI
PIGLIT: {'result': 'fail' }

Reproduce steps:
----------------
1. start X
2. ./bin/draw-vertices-2101010 -auto
Comment 1 Kenneth Graunke 2013-01-09 19:21:32 UTC 
Hmm.  This seems very believable, but I just retested it and it's working fine on my Haswell machine...
Comment 2 Gordon Jin 2013-04-01 05:48:54 UTC 
Hua, does it happen on all our HSW?
Comment 3 lu hua 2013-04-01 06:13:35 UTC 
(In reply to comment #2)
> Hua, does it happen on all our HSW?


Yes, It still fails.
Comment 4 Eric Anholt 2013-04-10 22:13:16 UTC 
Fails on my hsw -- I assume it's an issue related to the equation differences in bf75a1f09
Comment 5 Kenneth Graunke 2013-07-26 19:55:42 UTC 
Okay, I can reproduce this finally.  Not sure why I couldn't earlier.

At least this means both Haswell and Bay Trail follow the same rules.
Comment 6 Ian Romanick 2013-08-01 17:15:33 UTC 
Ken,

You did some triage on this, and there was some discussion on IRC.  What was the outcome?
Comment 7 Ian Romanick 2013-08-15 21:54:06 UTC 
It looks like the test just needs to be updated to accept either decoding of 10-bit floats.
Comment 8 Ian Romanick 2013-08-22 03:53:22 UTC 
Since this is a test error, I'm decreasing the severity and removing from the release tracker.
Comment 9 Kenneth Graunke 2018-01-10 18:32:46 UTC 
Fixed by piglit commit:

commit 35daaa1695ea01eb85bc02f9be9b6ebd1a7113a1
Author: Kenneth Graunke <kenneth@whitecape.org>
Date:   Mon Dec 25 21:10:16 2017 -0800

    draw-vertices-2101010: Accept either SNORM conversion formula.
    
    OpenGL defines two equations for converting from signed-normalized
    to floating point data.  These are:
    
        f = (2c + 1)/(2^b - 1)                (equation 2.2)
        f = max{c/2^(b-1) - 1), -1.0}         (equation 2.3)
    
    ARB_vertex_type_2_10_10_10_rev specifies equation 2.2 is to be used.
    
    However, OpenGL 4.2 switched to use equation 2.3 in all scenarios.
    This matched an earlier OpenGL ES 3.0 decision to only have one formula,
    as well as a DirectX decision to change to equation 2.3.  Some hardware
    also only supports equation 2.3.  So, basically no one can rely on
    equation 2.2 happening, and some people do rely on 2.3.
    
    This patch continues to require equation 2.3 for GL 4.2+, but relaxes
    the test to allow either behavior for earlier GL versions.
    
    See the following discussion for more details:
    https://lists.freedesktop.org/archives/mesa-dev/2013-August/042680.html
    
    This makes this test pass on i965 with Haswell and later.
    
    Reviewed-by: Roland Scheidegger <sroland@vmware.com>

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