Nouveau - May 2015 - [Bug 90363] New: [nv50] HW state is not reset correctly when using a new GL context

https://bugs.freedesktop.org/show_bug.cgi?id=90363

            Bug ID: 90363
           Summary: [nv50] HW state is not reset correctly when using a
                    new GL context
           Product: Mesa
           Version: git
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Drivers/DRI/nouveau
          Assignee: nouveau at lists.freedesktop.org
          Reporter: matteo.mystral at gmail.com
        QA Contact: nouveau at lists.freedesktop.org

Created attachment 115622
  --> https://bugs.freedesktop.org/attachment.cgi?id=115622&action=edit
Hack

Hardware state is not reset correctly when a process makes use of a new GL
context, after it has used and then destroyed the previous one.
This manifests in a (still uncommitted,
https://www.winehq.org/pipermail/wine-patches/2015-April/138974.html) Wine test
which fails on nv50. Actually commenting out stream_test(), which makes use of
instanced draws with ARB_instanced_arrays, workarounds the issue.
A single process executes both tests, destroying and then recreating a GL
context in between. AFAIU specifically the per-instance enable flags are never
reset on the HW and that breaks the latter test.

I'm attaching a patch which "fixes" the issue for me but it's
not the correct
approach.

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https://bugs.freedesktop.org/show_bug.cgi?id=90363

--- Comment #1 from Matteo Bruni <matteo.mystral at gmail.com> ---
Created attachment 115623
  --> https://bugs.freedesktop.org/attachment.cgi?id=115623&action=edit
Ilia's attempted fix

I'm attaching Ilia's patch for this issue, from IRC. It doesn't work
for me
(yet) but this should be more like the correct fix.

BTW, I can try to make a standalone, GL testcase for this bug. It might take a
while though.

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--- Comment #2 from Matteo Bruni <matteo.mystral at gmail.com> ---
Created attachment 115624
  --> https://bugs.freedesktop.org/attachment.cgi?id=115624&action=edit
Improved fix

The attached works for me. It's the patch from Ilia with an additional state
copy in nv50_create.

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--- Comment #3 from Ilia Mirkin <imirkin at alum.mit.edu> ---
Ah yeah, that makes sense. Forgot that contexts liked to auto-attach
themselves. cur_state seems like a dumb name, I'm going to change it to
saved_state or something. Also that state needs to be initialized, so I'm
going
to move the state init bits from that state init function to the screen init.
Will send a proper patch for testing tonight-ish.

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Ilia Mirkin <imirkin at alum.mit.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #4 from Ilia Mirkin <imirkin at alum.mit.edu> ---
Just pushed out the fixes to make it work on nv50 and nvc0. nvc0 had the
additional bug that 3d-engine-based blits use a vbo, and were also forgetting
to overwrite these attributes, leading to a fail even when having the proper
"state".

Thanks for reporting!

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