[PATCH v3 5/8] drm/i915/reset: remove I915_RESET_MODESET flag

[Jani Nikula <jani.nikula@xxxxxxxxx>]

Since commit d59cf7bb73f3 ("drm/i915/display: Use dma_fence interfaces
instead of i915_sw_fence") we don't have anyone waiting on the
I915_RESET_MODESET bit, and there's no need for its semantics. Instead,
simply return true from intel_display_reset_prepare() to indicate that
intel_display_reset_finish() should be called.

Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
---
 .../drm/i915/display/intel_display_reset.c    | 24 +++++++------------
 .../drm/i915/display/intel_display_reset.h    |  2 +-
 drivers/gpu/drm/i915/gt/intel_reset.c         |  8 ++++---
 drivers/gpu/drm/i915/gt/intel_reset_types.h   |  3 +--
 4 files changed, 15 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_reset.c b/drivers/gpu/drm/i915/display/intel_display_reset.c
index 121679b4230f..acc728c75328 100644
--- a/drivers/gpu/drm/i915/display/intel_display_reset.c
+++ b/drivers/gpu/drm/i915/display/intel_display_reset.c
@@ -27,7 +27,8 @@ bool intel_display_reset_test(struct intel_display *display)
 	return display->params.force_reset_modeset_test;
 }
 
-void intel_display_reset_prepare(struct intel_display *display)
+/* returns true if intel_display_reset_finish() needs to be called */
+bool intel_display_reset_prepare(struct intel_display *display)
 {
 	struct drm_i915_private *dev_priv = to_i915(display->drm);
 	struct drm_modeset_acquire_ctx *ctx = &display->restore.reset_ctx;
@@ -35,17 +36,12 @@ void intel_display_reset_prepare(struct intel_display *display)
 	int ret;
 
 	if (!HAS_DISPLAY(display))
-		return;
+		return false;
 
 	/* reset doesn't touch the display */
 	if (!intel_display_reset_test(display) &&
 	    !gpu_reset_clobbers_display(display))
-		return;
-
-	/* We have a modeset vs reset deadlock, defensively unbreak it. */
-	set_bit(I915_RESET_MODESET, &to_gt(dev_priv)->reset.flags);
-	smp_mb__after_atomic();
-	wake_up_bit(&to_gt(dev_priv)->reset.flags, I915_RESET_MODESET);
+		return false;
 
 	if (atomic_read(&display->restore.pending_fb_pin)) {
 		drm_dbg_kms(display->drm,
@@ -75,7 +71,7 @@ void intel_display_reset_prepare(struct intel_display *display)
 		ret = PTR_ERR(state);
 		drm_err(display->drm, "Duplicating state failed with %i\n",
 			ret);
-		return;
+		return true;
 	}
 
 	ret = drm_atomic_helper_disable_all(display->drm, ctx);
@@ -83,11 +79,13 @@ void intel_display_reset_prepare(struct intel_display *display)
 		drm_err(display->drm, "Suspending crtc's failed with %i\n",
 			ret);
 		drm_atomic_state_put(state);
-		return;
+		return true;
 	}
 
 	display->restore.modeset_state = state;
 	state->acquire_ctx = ctx;
+
+	return true;
 }
 
 void intel_display_reset_finish(struct intel_display *display)
@@ -100,10 +98,6 @@ void intel_display_reset_finish(struct intel_display *display)
 	if (!HAS_DISPLAY(display))
 		return;
 
-	/* reset doesn't touch the display */
-	if (!test_bit(I915_RESET_MODESET, &to_gt(i915)->reset.flags))
-		return;
-
 	state = fetch_and_zero(&display->restore.modeset_state);
 	if (!state)
 		goto unlock;
@@ -141,6 +135,4 @@ void intel_display_reset_finish(struct intel_display *display)
 	drm_modeset_drop_locks(ctx);
 	drm_modeset_acquire_fini(ctx);
 	mutex_unlock(&display->drm->mode_config.mutex);
-
-	clear_bit_unlock(I915_RESET_MODESET, &to_gt(i915)->reset.flags);
 }
diff --git a/drivers/gpu/drm/i915/display/intel_display_reset.h b/drivers/gpu/drm/i915/display/intel_display_reset.h
index c1dd2e8d0914..311b5af8ca0c 100644
--- a/drivers/gpu/drm/i915/display/intel_display_reset.h
+++ b/drivers/gpu/drm/i915/display/intel_display_reset.h
@@ -11,7 +11,7 @@
 struct intel_display;
 
 bool intel_display_reset_test(struct intel_display *display);
-void intel_display_reset_prepare(struct intel_display *display);
+bool intel_display_reset_prepare(struct intel_display *display);
 void intel_display_reset_finish(struct intel_display *display);
 
 #endif /* __INTEL_RESET_H__ */
diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
index 835c9081b239..f6c8e4d48b04 100644
--- a/drivers/gpu/drm/i915/gt/intel_reset.c
+++ b/drivers/gpu/drm/i915/gt/intel_reset.c
@@ -1419,12 +1419,14 @@ static void intel_gt_reset_global(struct intel_gt *gt,
 	intel_wedge_on_timeout(&w, gt, 60 * HZ) {
 		struct drm_i915_private *i915 = gt->i915;
 		struct intel_display *display = &i915->display;
+		bool reset_display;
 
-		intel_display_reset_prepare(display);
+		reset_display = intel_display_reset_prepare(display);
 
 		intel_gt_reset(gt, engine_mask, reason);
 
-		intel_display_reset_finish(display);
+		if (reset_display)
+			intel_display_reset_finish(display);
 	}
 
 	if (!test_bit(I915_WEDGED, &gt->reset.flags))
@@ -1492,7 +1494,7 @@ void intel_gt_handle_error(struct intel_gt *gt,
 	    intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
 		local_bh_disable();
 		for_each_engine_masked(engine, gt, engine_mask, tmp) {
-			BUILD_BUG_ON(I915_RESET_MODESET >= I915_RESET_ENGINE);
+			BUILD_BUG_ON(I915_RESET_BACKOFF >= I915_RESET_ENGINE);
 			if (test_and_set_bit(I915_RESET_ENGINE + engine->id,
 					     &gt->reset.flags))
 				continue;
diff --git a/drivers/gpu/drm/i915/gt/intel_reset_types.h b/drivers/gpu/drm/i915/gt/intel_reset_types.h
index 80351f0a856c..4f5fd393af6f 100644
--- a/drivers/gpu/drm/i915/gt/intel_reset_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_reset_types.h
@@ -41,8 +41,7 @@ struct intel_reset {
 	 */
 	unsigned long flags;
 #define I915_RESET_BACKOFF	0
-#define I915_RESET_MODESET	1
-#define I915_RESET_ENGINE	2
+#define I915_RESET_ENGINE	1
 #define I915_WEDGED_ON_INIT	(BITS_PER_LONG - 3)
 #define I915_WEDGED_ON_FINI	(BITS_PER_LONG - 2)
 #define I915_WEDGED		(BITS_PER_LONG - 1)
-- 
2.39.5