[Intel-gfx] [PATCH] intel: initialize bufmgr.bo_mrb_exec unconditionally

[Albert Damen]

After upgrading xf86-video-intel to git master X didn't work anymore
(black screen, only mouse cursor visible and moving). Xorg.0.log shows
many errors:
(EE) intel(0): Failed to submit batch buffer, expect rendering
corruption or even a frozen display: No such device.

This seems to be caused by commit 'add BLT ring support' which calls
drm_intel_bo_mrb_exec instead of dri_bo_exec in intel_batch_submit.
drm_intel_bo_mrb_exec will try to call bo->bufmgr->bo_mrb_exec but this
is only set if the kernel has support for BSD and/or BLT rings. My
kernel, 2.6.33, does not have this, so drm_intel_bo_mrb_exec returns
ENODEV.

Attached patch against libdrm solves the problem for me. It seems safe
to me to set bo_mrb_exec unconditionally as drm_intel_gem_bo_mrb_exec2
will still check if BSD and BLT rings can be used.

Best regards,
Albert Damen