[Intel-gfx] [PATCH 1/2] drm/i915/guc: fix GuC suspend/resume

[Daniele Ceraolo Spurio]

The ENTER/EXIT_S_STATE actions queue the save/restore operation in GuC
FW and then return, so waiting on the H2H is not enough to guarantee
GuC is done.
When all the processing is done, GuC writes 0 to scratch register 14,
so we can poll on that. Note that GuC does not ensure that the value
in the register is different from 0 while the action is in progress
so we need to take care of that ourselves as well.

Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
---
 drivers/gpu/drm/i915/intel_guc.c      | 28 +++++++++++++++++++++++++--
 drivers/gpu/drm/i915/intel_guc_fwif.h |  6 ++++++
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_guc.c b/drivers/gpu/drm/i915/intel_guc.c
index 230aea69385d..f238cd7a9dcf 100644
--- a/drivers/gpu/drm/i915/intel_guc.c
+++ b/drivers/gpu/drm/i915/intel_guc.c
@@ -521,6 +521,30 @@ int intel_guc_auth_huc(struct intel_guc *guc, u32 rsa_offset)
 	return intel_guc_send(guc, action, ARRAY_SIZE(action));
 }
 
+/*
+ * The ENTER/EXIT_S_STATE actions queue the save/restore operation in GuC FW and
+ * then return, so waiting on the H2H is not enough to guarantee GuC is done.
+ * When all the processing is done, GuC writes 0 to scratch register 14, so we
+ * can poll on that. Note that GuC does not ensure that the value in the
+ * register is different from 0 while the action is in progress so we need to
+ * take care of that ourselves as well.
+ */
+static int guc_sleep_state_action(struct intel_guc *guc,
+				  const u32 *action, u32 len)
+{
+	struct drm_i915_private *dev_priv = guc_to_i915(guc);
+	int ret;
+
+	I915_WRITE(SOFT_SCRATCH(14), ~0x0);
+
+	ret = intel_guc_send(guc, action, len);
+	if (ret)
+		return ret;
+
+	return intel_wait_for_register(dev_priv, SOFT_SCRATCH(14), ~0x0,
+				       INTEL_GUC_SLEEP_STATE_SUCCESS, 10);
+}
+
 /**
  * intel_guc_suspend() - notify GuC entering suspend state
  * @guc:	the guc
@@ -533,7 +557,7 @@ int intel_guc_suspend(struct intel_guc *guc)
 		intel_guc_ggtt_offset(guc, guc->shared_data)
 	};
 
-	return intel_guc_send(guc, data, ARRAY_SIZE(data));
+	return guc_sleep_state_action(guc, data, ARRAY_SIZE(data));
 }
 
 /**
@@ -571,7 +595,7 @@ int intel_guc_resume(struct intel_guc *guc)
 		intel_guc_ggtt_offset(guc, guc->shared_data)
 	};
 
-	return intel_guc_send(guc, data, ARRAY_SIZE(data));
+	return guc_sleep_state_action(guc, data, ARRAY_SIZE(data));
 }
 
 /**
diff --git a/drivers/gpu/drm/i915/intel_guc_fwif.h b/drivers/gpu/drm/i915/intel_guc_fwif.h
index 8382d591c784..b0eb5aabe0a7 100644
--- a/drivers/gpu/drm/i915/intel_guc_fwif.h
+++ b/drivers/gpu/drm/i915/intel_guc_fwif.h
@@ -687,6 +687,12 @@ enum intel_guc_report_status {
 	INTEL_GUC_REPORT_STATUS_COMPLETE = 0x4,
 };
 
+enum intel_guc_sleep_state_status {
+	INTEL_GUC_SLEEP_STATE_SUCCESS = 0x0,
+	INTEL_GUC_SLEEP_STATE_PREEMPT_TO_IDLE_FAILED = 0x1,
+	INTEL_GUC_SLEEP_STATE_ENGINE_RESET_FAILED = 0x2
+};
+
 #define GUC_LOG_CONTROL_LOGGING_ENABLED	(1 << 0)
 #define GUC_LOG_CONTROL_VERBOSITY_SHIFT	4
 #define GUC_LOG_CONTROL_VERBOSITY_MASK	(0xF << GUC_LOG_CONTROL_VERBOSITY_SHIFT)
-- 
2.19.0