[Intel-gfx] [PATCH] drm/i915/uc: don't enable communication twice on resume

[Daniele Ceraolo Spurio]

When coming out of S3/S4 we sanitize and re-init the HW, which includes
enabling communication during uc_init_hw. We therefore don't want to do
that again in uc_resume and can just tell GuC to reload its state.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gt/uc/intel_uc.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
index fafa9be1e12a..34706a753793 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
@@ -233,11 +233,18 @@ static void guc_disable_interrupts(struct intel_guc *guc)
 	guc->interrupts.disable(guc);
 }
 
+static bool guc_communication_enabled(struct intel_guc *guc)
+{
+	return guc->send != intel_guc_send_nop;
+}
+
 static int guc_enable_communication(struct intel_guc *guc)
 {
 	struct drm_i915_private *i915 = guc_to_gt(guc)->i915;
 	int ret;
 
+	GEM_BUG_ON(guc_communication_enabled(guc));
+
 	ret = intel_guc_ct_enable(&guc->ct);
 	if (ret)
 		return ret;
@@ -558,7 +565,14 @@ int intel_uc_resume(struct intel_uc *uc)
 	if (!intel_guc_is_running(guc))
 		return 0;
 
-	guc_enable_communication(guc);
+	/*
+	 * When coming out of S3/S4 we sanitize and re-init the HW, so
+	 * communication is already re-enabled at this point and we just need
+	 * to tell GuC to reload its internal state. During runtime resume we
+	 * instead want to re-init everything.
+	 */
+	if (!guc_communication_enabled(guc))
+		guc_enable_communication(guc);
 
 	err = intel_guc_resume(guc);
 	if (err) {
-- 
2.22.0