[Intel-gfx] [PATCH 3/3] drm/i915: Make module param for MMIO flip selection as tristate

[Chris Wilson]

I was thinking this patch should be more like

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 3201495..ab9b5f7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2060,7 +2060,7 @@ struct i915_params {
 	bool reset;
 	bool disable_display;
 	bool disable_vtd_wa;
-	bool use_mmio_flip;
+	int use_mmio_flip;
 };
 extern struct i915_params i915 __read_mostly;
 
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index e0d44df..6d7c580 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -158,5 +158,5 @@ module_param_named(enable_cmd_parser, i915.enable_cmd_parser, int, 0600);
 MODULE_PARM_DESC(enable_cmd_parser,
 		 "Enable command parsing (1=enabled [default], 0=disabled)");
 
-module_param_named(use_mmio_flip, i915.use_mmio_flip, bool, 0600);
-MODULE_PARM_DESC(use_mmio_flip, "use MMIO flips (default: false)");
+module_param_named(use_mmio_flip, i915.use_mmio_flip, int, 0600);
+MODULE_PARM_DESC(use_mmio_flip, "use MMIO flips (-1=never, 0=driver discretion [default], 1=always)");
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index ac93ae4..b6c8fce 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9207,24 +9207,24 @@ static int intel_gen7_queue_flip(struct drm_device *dev,
 	return 0;
 }
 
-static bool intel_use_mmio_flip(struct drm_device *dev)
+static bool use_mmio_flip(struct intel_engine_cs *ring,
+			  struct drm_i915_gem_object *obj)
 {
-	/* If module parameter is disabled, use CS flips.
-	 * Otherwise, use MMIO flips starting from Gen5.
-	 * This is not being used for older platforms, because
+	/* This is not being used for older platforms, because
 	 * non-availability of flip done interrupt forces us to use
 	 * CS flips. Older platforms derive flip done using some clever
 	 * tricks involving the flip_pending status bits and vblank irqs.
 	 * So using MMIO flips there would disrupt this mechanism.
 	 */
-
-	if (i915.use_mmio_flip == 0)
+	if (INTEL_INFO(dev)->gen < 5)
 		return false;
 
-	if (INTEL_INFO(dev)->gen >= 5)
+	if (i915.use_mmio_flip < 0)
+		return false;
+	else if (i915.use_mmio_flip > 0)
 		return true;
 	else
-		return false;
+		return ring != obj->ring;
 }
 
 static void intel_do_mmio_flip(struct intel_crtc *intel_crtc)
@@ -9290,9 +9290,9 @@ void intel_notify_mmio_flip(struct intel_engine_cs *ring)
 		struct intel_mmio_flip *mmio_flip;
 
 		mmio_flip = &intel_crtc->mmio_flip;
-
 		if (mmio_flip->seqno == 0)
 			continue;
+
 		if (ring->id != mmio_flip->ring_id)
 			continue;
 
@@ -9306,26 +9306,25 @@ void intel_notify_mmio_flip(struct intel_engine_cs *ring)
 }
 
 static int intel_queue_mmio_flip(struct drm_device *dev,
-			struct drm_crtc *crtc,
-			struct drm_framebuffer *fb,
-			struct drm_i915_gem_object *obj,
-			struct intel_engine_cs *ring,
-			uint32_t flags)
+				 struct drm_crtc *crtc,
+				 struct drm_framebuffer *fb,
+				 struct drm_i915_gem_object *obj,
+				 struct intel_engine_cs *ring,
+				 uint32_t flags)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	unsigned long irq_flags;
 	int ret;
 
-	if (WARN_ON(intel_crtc->mmio_flip.seqno)) {
-		ret = -EBUSY;
-		goto err;
-	}
+	if (WARN_ON(intel_crtc->mmio_flip.seqno))
+		return -EBUSY;
 
 	ret = intel_postpone_flip(obj);
-	if (ret < 0) {
-		goto err;
-	} else if (ret == 0) {
+	if (ret < 0)
+		return ret;
+
+	if (ret == 0) {
 		intel_do_mmio_flip(intel_crtc);
 		return 0;
 	}
@@ -9340,8 +9339,6 @@ static int intel_queue_mmio_flip(struct drm_device *dev,
 	 */
 	intel_notify_mmio_flip(obj->ring);
 	return 0;
-err:
-	return ret;
 }
 
 static int intel_default_queue_flip(struct drm_device *dev,
@@ -9529,7 +9526,10 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 		i915_gem_obj_ggtt_offset(obj) + intel_crtc->dspaddr_offset;
 	work->enable_stall_check = true;
 
-	ret = dev_priv->display.queue_flip(dev, crtc, fb, obj, ring, page_flip_flags);
+	if (use_mmio_flip(ring, obj))
+		ret = intel_queue_mmio_flip(ring, obj)(dev, crtc, fb, obj, ring, page_flip_flags);
+	else
+		ret = dev_priv->display.queue_flip(dev, crtc, fb, obj, ring, page_flip_flags);
 	if (ret)
 		goto cleanup_unpin;
 
@@ -11775,9 +11775,6 @@ static void intel_init_display(struct drm_device *dev)
 		break;
 	}
 
-	if (intel_use_mmio_flip(dev))
-		dev_priv->display.queue_flip = intel_queue_mmio_flip;
-
 	intel_panel_init_backlight_funcs(dev);
 }
 
and squashed into the first. You can have a reviewed-by after that and 
I'll try and get a t-b.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre