[Intel-gfx] [PATCH 1/5] drm/i915: Cleanup instdone state

[Ben Widawsky]

Clear the cached instdone state to match what we expect from hardware
and prevent us from comparing stale values.

Actually, clearing the state is not the same as setting idle state.
There would be a known state of idle (ie. all units are done), but since
it differs for every platform, we can just set 0, and let the hangcheck
progress as normal.

By putting the clear into add_request we are essentially initializing
the cached instdone to a known state before we start the hangcheck
timer.

v2: clear instdone in more place (Chris)
Rewrote the commit message

References: https://bugs.freedesktop.org/show_bug.cgi?id=52429
Tested-by: Guang A Yang <guang.a.yang at intel.com>
Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_gem.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0514593..0d992e6 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1601,6 +1601,7 @@ i915_add_request(struct intel_ring_buffer *ring,
 
 	if (!dev_priv->mm.suspended) {
 		if (i915_enable_hangcheck) {
+			dev_priv->last_instdone = dev_priv->last_instdone1 = 0;
 			mod_timer(&dev_priv->hangcheck_timer,
 				  jiffies +
 				  msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
-- 
1.7.11.4