[Intel-gfx] [PATCH] drm/i915/guc: Skip suspend/resume GuC action on platforms w/o GuC submission

[don.hiatt at intel.com]

From: Don Hiatt <don.hiatt at intel.com>

On some platforms (e.g. KBL) that do not support GuC submission, but
the user enabled the GuC communication (e.g for HuC authentication)
calling the GuC EXIT_S_STATE action results in lose of ability to
enter RC6. We can remove the GuC suspend/resume entirely as we do
not need to save the GuC submission status.

Add intel_guc_submission_is_enabled() function to determine if
GuC submission is active.

v2: Do not suspend/resume the GuC on platforms that do not support
    Guc Submission.
v3: Fix typo, move suspend logic to remove goto.
v4: Use intel_guc_submission_is_enabled() to check GuC submission
    status.
v5: No need to look at engine to determine if submission is enabled.
    Squash fix + intel_guc_submission_is_enabled() patch into one.

Reported-by: KiteStramuort <kitestramuort at autistici.org>
Reported-by: S. Zharkoff <s.zharkoff at gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111594
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111623
Fixes: f774f0964919 ("drm/i915/guc: Turn on GuC/HuC auto mode")
Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
Cc: Daniele Ceralo Spurio <daniele.ceraolospurio at intel.com>
Cc: Stuart Summers <stuart.summers at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Tested-by: Tomas Janousek <tomi at nomi.cz>
Signed-off-by: Don Hiatt <don.hiatt at intel.com>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc.c | 7 +++++++
 drivers/gpu/drm/i915/gt/uc/intel_uc.c  | 8 ++++++++
 drivers/gpu/drm/i915/i915_drv.h        | 6 ++++++
 3 files changed, 21 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
index 019ae6486e8d..92d9305c0d73 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
@@ -553,6 +553,13 @@ int intel_guc_suspend(struct intel_guc *guc)
 		GUC_POWER_D1, /* any value greater than GUC_POWER_D0 */
 	};
 
+	/*
+	 * If GuC communication is enabled but submission is not supported,
+	 * we do not need to suspend the GuC.
+	 */
+	if (!intel_guc_submission_is_enabled(guc))
+		return 0;
+
 	/*
 	 * The ENTER_S_STATE action queues the save/restore operation in GuC FW
 	 * and then returns, so waiting on the H2G is not enough to guarantee
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
index 629b19377a29..4dd43b99a334 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
@@ -605,6 +605,14 @@ static int __uc_resume(struct intel_uc *uc, bool enable_communication)
 	if (enable_communication)
 		guc_enable_communication(guc);
 
+	/*
+	 * If GuC communication is enabled but submission is not supported,
+	 * we do not need to resume the GuC but we do need to enable the
+	 * GuC communication on resume (above).
+	 */
+	if (!intel_guc_submission_is_enabled(guc))
+		return 0;
+
 	err = intel_guc_resume(guc);
 	if (err) {
 		DRM_DEBUG_DRIVER("Failed to resume GuC, err=%d", err);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 7bc1d8c102b2..2b879472e760 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2044,4 +2044,10 @@ i915_coherent_map_type(struct drm_i915_private *i915)
 	return HAS_LLC(i915) ? I915_MAP_WB : I915_MAP_WC;
 }
 
+static inline bool intel_guc_submission_is_enabled(struct intel_guc *guc)
+{
+	return intel_guc_is_submission_supported(guc) &&
+		intel_guc_is_running(guc);
+}
+
 #endif
-- 
2.20.1