[Mesa-dev] [PATCH] r300g: only allow byteswapped formats on big endian

[Marek Olšák]

I'd like some evidence that the bug is caused by r300g and not some common
code.

Marek

On Feb 13, 2017 12:10 PM, "Grazvydas Ignotas" <notasas at gmail.com> wrote:

> On Mon, Feb 13, 2017 at 10:22 AM, Michel Dänzer <michel at daenzer.net>
> wrote:
> > On 13/02/17 05:17 PM, Michel Dänzer wrote:
> >> On 11/02/17 08:01 AM, Grazvydas Ignotas wrote:
> >>> They cause regressions on little endian.
> >>>
> >>> Fixes: 172bfdaa9e ("r300g: add support for PIPE_FORMAT_x8R8G8B8_*")
> >>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98869
> >>> Signed-off-by: Grazvydas Ignotas <notasas at gmail.com>
> >>> ---
> >>> no commit access
> >>>
> >>>  src/gallium/drivers/r300/r300_texture.c | 5 +++++
> >>>  1 file changed, 5 insertions(+)
> >>>
> >>> diff --git a/src/gallium/drivers/r300/r300_texture.c
> b/src/gallium/drivers/r300/r300_texture.c
> >>> index fbac07a..929c3fe 100644
> >>> --- a/src/gallium/drivers/r300/r300_texture.c
> >>> +++ b/src/gallium/drivers/r300/r300_texture.c
> >>> @@ -47,6 +47,11 @@
> >>>   */
> >>>  static enum pipe_format r300_unbyteswap_array_format(enum
> pipe_format format)
> >>>  {
> >>> +    /* FIXME: Disabled on little endian because of a reported
> regression:
> >>> +     * https://bugs.freedesktop.org/show_bug.cgi?id=98869 */
> >>> +    if (PIPE_ENDIAN_NATIVE != PIPE_ENDIAN_BIG)
> >>> +        return format;
> >>
> >> Is there any reason to believe that whatever issue this avoids couldn't
> >> happen on big endian hosts as well?
>
> I don't know...
>
> > More to the point, this seems to disable part of the logic needed for
> > supporting PIPE_FORMAT_x8R8G8B8_* on little endian, but leaves those
> > formats advertised as supported.
>
> Well it just reverts to an earlier working state before Marek's patch
> (172bfdaa9e) tor LE.
> The patch in question which added support for those formats hasn't
> done anything specific related to advertising them, and
> r300_is_*_supported() end up indirectly calling
> r300_unbyteswap_array_format(), so it looks like nothing specific is
> needed for advertisement?
>
> > Did you confirm that there are no
> > piglit gpu profile regressions with this patch?
>
> I don't have the hardware and can't test, I just have confirmation
> from a user that the regression gets fixed.
>
> Gražvydas
>
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