[Bug 79948] New: [i965] Incorrect pixels when using discard and uniform loads

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Thu Jun 12 11:47:36 PDT 2014


https://bugs.freedesktop.org/show_bug.cgi?id=79948

          Priority: medium
            Bug ID: 79948
          Assignee: idr at freedesktop.org
           Summary: [i965] Incorrect pixels when using discard and uniform
                    loads
        QA Contact: intel-3d-bugs at lists.freedesktop.org
          Severity: normal
    Classification: Unclassified
                OS: Linux (All)
          Reporter: cody at lunarg.com
          Hardware: x86-64 (AMD64)
            Status: NEW
           Version: git
         Component: Drivers/DRI/i965
           Product: Mesa

Created attachment 100932
  --> https://bugs.freedesktop.org/attachment.cgi?id=100932&action=edit
Patch to piglit test showing the discard problem.

Commit 17c7ead7 exposed a bug in how uniform loading happens in the presence of
discard.  It manifested itself in an application as randomly incorrect pixels
on the borders of conditional areas.

We've boiled it down to a piglit test case, attached as a patch to existing
test.  When you run it on HSW with mesa 10.2 or later, notice the white line
along the diagonal axis.  That shouldn't be there.  The white is coming from a
texture sample to make it easy to see the problem.  It should have been
multiplied by the uniform values as the rest of the fragments were.  The key
bits are in the second fragment shader.

I believe we've root caused it and I'll next attach a fix that I'll send to the
mesa-dev list.

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/intel-3d-bugs/attachments/20140612/74dd171c/attachment-0001.html>


More information about the intel-3d-bugs mailing list