[Intel-gfx] [PATCH 2/2] drm/i915/gt: Clear rc6 residency trackers across suspend

[Chris Wilson]

On suspend, the rc6 residency counters (stored in HW registers) will be
lost and cleared. However, we keep track of the rc6 residency to provide
a continuous 64b sampling, and if we see the HW value go backwards, we
assume it overflowed and add on 32b/40b -- an interesting artifact when
sampling across suspend.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/gt/intel_rc6.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_rc6.c b/drivers/gpu/drm/i915/gt/intel_rc6.c
index 9e303c29d6e3..04eeb7740e53 100644
--- a/drivers/gpu/drm/i915/gt/intel_rc6.c
+++ b/drivers/gpu/drm/i915/gt/intel_rc6.c
@@ -542,6 +542,8 @@ void intel_rc6_init(struct intel_rc6 *rc6)
 
 void intel_rc6_sanitize(struct intel_rc6 *rc6)
 {
+	memset(rc6->prev_hw_residency, 0, sizeof(rc6->prev_hw_residency));
+
 	if (rc6->enabled) { /* unbalanced suspend/resume */
 		rpm_get(rc6);
 		rc6->enabled = false;
-- 
2.25.0.rc2