[PATCH v3 0/3] Reduce context clear batch size to avoid gpu hang

[rwright at hpe.com]

From: Randy Wright <rwright at hpe.com>

For several months, I've been experiencing GPU hangs when  starting
Cinnamon on an HP Pavilion Mini 300-020 if I try to run an upstream
kernel.  I reported this recently in
https://gitlab.freedesktop.org/drm/intel/-/issues/2413 where I have
attached the requested evidence including the state collected from
/sys/class/drm/card0/error and debug output from dmesg.

I ran a bisect to find the problem, which indicates this is the
troublesome commit:

  [47f8253d2b8947d79fd3196bf96c1959c0f25f20] drm/i915/gen7: Clear all EU/L3 residual contexts

The nature of that commit suggested to me that reducing the
batch size used in the context clear operation might help this
relatively low-powered system to avoid the hang.... and it did!
I simply forced this system to take the smaller batch length that is
already used for non-Haswell systems.

The first two versions of this patch were posted as RFC
patches to the Intel-gfx list, implementing the same
algorithmic change in function batch_get_defaults,
but without employing a properly constructed quirk.

I've now cleaned up the patch to employ a new QUIRK_RENDERCLEAR_REDUCED.
The quirk is presently set only for the aforementioned HP Pavilion Mini
300-020.  The patch now touches three files to define the quirk, set it,
and then check for it in function batch_get_defaults.

Randy Wright (3):
  drm/i915: Introduce quirk QUIRK_RENDERCLEAR_REDUCED
  drm/i915/display: Add function quirk_renderclear_reduced
  drm/i915/gt: Force reduced batch size if new QUIRK_RENDERCLEAR_REDUCED
    is set.

 drivers/gpu/drm/i915/display/intel_quirks.c | 13 +++++++++++++
 drivers/gpu/drm/i915/gt/gen7_renderclear.c  |  2 +-
 drivers/gpu/drm/i915/i915_drv.h             |  1 +
 3 files changed, 15 insertions(+), 1 deletion(-)

-- 
2.25.1