]> git.baikalelectronics.ru Git - kernel.git/commit
drm/i915/perf: avoid read back of head register
authorRobert Bragg <robert@sixbynine.org>
Thu, 11 May 2017 15:43:26 +0000 (16:43 +0100)
committerChris Wilson <chris@chris-wilson.co.uk>
Sat, 13 May 2017 09:59:39 +0000 (10:59 +0100)
commit29936932cb8284eaef60ba5c85b316ef50ce4fd5
treecf8d18fb92512d320d5b7f13d54b8f9f3f281f62
parente450f142e1b558158d9e689f8cdb8279155da144
drm/i915/perf: avoid read back of head register

There's no need for the driver to keep reading back the head pointer
from hardware since the hardware doesn't update it automatically. This
way we can treat any invalid head pointer value as a software/driver
bug instead of spurious hardware behaviour.

This change is also a small stepping stone towards re-working how
the head and tail state is managed as part of an improved workaround
for the tail register race condition.

Signed-off-by: Robert Bragg <robert@sixbynine.org>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511154345.962-4-lionel.g.landwerlin@intel.com
drivers/gpu/drm/i915/i915_drv.h
drivers/gpu/drm/i915/i915_perf.c