[Intel-gfx] [PATCH 3/3] drm/i915/execlists: Reset CSB pointers on canceling requests (wedging)

[Chris Wilson]

The prior assumption was that we did not need to reset the CSB on
wedging when cancelling the outstanding requests as it would be cleaned
up in the subsequent reset prior to restarting the GPU. However, what
was not accounted for was that in performing the reset, we would try to
process the outstanding CSB entries. If the GPU happened to complete a
CS event just as we were performing the cancellation of requests, that
event would be kept in the CSB until the reset -- but our bookkeeping
was cleared, causing confusion when trying to complete the CS event.

v2: Use a sanitize on unwedge to avoid interfering with eio suspend
(where we intentionally disable GPU reset).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107925
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d6f2bbd6a0dc..c8020719bcfb 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3438,6 +3438,9 @@ bool i915_gem_unset_wedged(struct drm_i915_private *i915)
 	i915_retire_requests(i915);
 	GEM_BUG_ON(i915->gt.active_requests);
 
+	if (!intel_gpu_reset(i915, ALL_ENGINES))
+		intel_engines_sanitize(i915);
+
 	/*
 	 * Undo nop_submit_request. We prevent all new i915 requests from
 	 * being queued (by disallowing execbuf whilst wedged) so having
-- 
2.19.0