[PATCH 6/9] drm/i915: Improve page flip vs. FBC interaction

[ville.syrjala@linux.intel.com]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

On FBC2 (CTG+) page flips will automagically nuke FBC, so the only thing
we need to do on page flip is update the CPU fence information.

On FBC1 we need to to disable+re-enable FBC around page flips. Previously
we just called intel_disable_fbc() + intel_update_fbc() to do that.
However intel_update_fbc() would actually need to grab all the modeset
locks, which we can't do from the driver workqueue. Make things a bit
more straightforward by simply disabling FBC only if it's active/scheduled
to be active on the current CRTC, and restart it on the same CRTC
after the flip.

FIXME: Several FBC1 docs actually seem to indicate that sync flips will
also cause a nuke on FBC1. Need to verify this.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c |  5 +-
 drivers/gpu/drm/i915/intel_drv.h     |  4 ++
 drivers/gpu/drm/i915/intel_pm.c      | 96 +++++++++++++++++++++++++++++++++++-
 3 files changed, 102 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 4155814..af0eafe 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -8222,7 +8222,7 @@ static void intel_unpin_work_fn(struct work_struct *__work)
 	drm_gem_object_unreference(&work->pending_flip_obj->base);
 	drm_gem_object_unreference(&work->old_fb_obj->base);
 
-	intel_update_fbc(dev);
+	intel_fbc_flip_end(work->crtc, work->crtc->fb);
 	mutex_unlock(&dev->struct_mutex);
 
 	BUG_ON(atomic_read(&to_intel_crtc(work->crtc)->unpin_work_count) == 0);
@@ -8661,7 +8661,8 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 	if (ret)
 		goto cleanup_pending;
 
-	intel_disable_fbc(dev);
+	intel_fbc_flip_start(crtc, fb);
+
 	intel_mark_fb_busy(obj, NULL);
 	mutex_unlock(&dev->struct_mutex);
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 119bb95..f9e9ca0 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -836,6 +836,10 @@ void intel_update_sprite_watermarks(struct drm_plane *plane,
 				    bool enabled, bool scaled);
 void intel_init_pm(struct drm_device *dev);
 bool intel_fbc_enabled(struct drm_device *dev);
+void intel_fbc_flip_start(struct drm_crtc *crtc,
+			  struct drm_framebuffer *fb);
+void intel_fbc_flip_end(struct drm_crtc *crtc,
+			struct drm_framebuffer *fb);
 void intel_update_fbc(struct drm_device *dev);
 void intel_gpu_ips_init(struct drm_i915_private *dev_priv);
 void intel_gpu_ips_teardown(void);
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 4039aa3..2a613ac 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -363,6 +363,8 @@ static void intel_enable_fbc(struct drm_crtc *crtc, unsigned long interval)
 	if (!dev_priv->display.enable_fbc)
 		return;
 
+	WARN_ON(dev_priv->fbc.fbc_work && dev_priv->fbc.plane != -1);
+
 	intel_cancel_fbc_work(dev_priv);
 
 	work = kzalloc(sizeof(*work), GFP_KERNEL);
@@ -401,6 +403,8 @@ void intel_disable_fbc(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	WARN_ON(dev_priv->fbc.fbc_work && dev_priv->fbc.plane != -1);
+
 	intel_cancel_fbc_work(dev_priv);
 
 	if (!dev_priv->display.disable_fbc)
@@ -414,6 +418,96 @@ void intel_disable_fbc(struct drm_device *dev)
 	}
 }
 
+static void intel_update_fbc_fb(struct drm_crtc *crtc,
+				struct drm_framebuffer *fb)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_fbc_work *work = dev_priv->fbc.fbc_work;
+
+	/*
+	 * If we've just scheduled an fbc work,
+	 * simply update the fb for the work.
+	 */
+	if (work) {
+		WARN_ON(dev_priv->fbc.plane != -1);
+
+		if (work->crtc != crtc)
+			return;
+
+		drm_framebuffer_reference(fb);
+		drm_framebuffer_unreference(work->fb);
+		work->fb = fb;
+	}
+
+	if (dev_priv->fbc.plane == to_intel_crtc(crtc)->plane) {
+		WARN_ON(dev_priv->fbc.fbc_work);
+
+		if (dev_priv->fbc.fb == fb &&
+		    dev_priv->fbc.y == crtc->y)
+			return;
+
+		intel_setup_fbc(crtc, fb, 500);
+	}
+}
+
+void intel_fbc_flip_start(struct drm_crtc *crtc,
+			  struct drm_framebuffer *fb)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_fbc_work *work = dev_priv->fbc.fbc_work;
+
+	if (!I915_HAS_FBC(dev))
+		return;
+
+	WARN_ON(work && dev_priv->fbc.plane != -1);
+
+	/* just need to update the CPU fence on FBC2 */
+	if (IS_G4X(dev) || INTEL_INFO(dev)->gen >= 5) {
+		intel_update_fbc_fb(crtc, fb);
+		return;
+	}
+
+	if (work && work->crtc == crtc) {
+		intel_cancel_fbc_work(dev_priv);
+
+		/*
+		 * set fbc.plane so that we can re-enable
+		 * FBC with just intel_fbc_flip_end().
+		 */
+		dev_priv->fbc.plane = to_intel_crtc(crtc)->plane;
+		return;
+	}
+
+	if (dev_priv->fbc.plane == to_intel_crtc(crtc)->plane) {
+		dev_priv->display.disable_fbc(dev);
+
+		/*
+		 * don't clear fbc.plane so that we can
+		 * re-enable FBC with just intel_fbc_flip_end().
+		 */
+	}
+}
+
+void intel_fbc_flip_end(struct drm_crtc *crtc,
+			struct drm_framebuffer *fb)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	if (!I915_HAS_FBC(dev))
+		return;
+
+	WARN_ON(dev_priv->fbc.fbc_work && dev_priv->fbc.plane != -1);
+
+	/* nothing to do on FBC2 */
+	if (IS_G4X(dev) || INTEL_INFO(dev)->gen >= 5)
+		return;
+
+	intel_update_fbc_fb(crtc, fb);
+}
+
 static bool set_no_fbc_reason(struct drm_i915_private *dev_priv,
 			      enum no_fbc_reason reason)
 {
@@ -567,7 +661,7 @@ void intel_update_fbc(struct drm_device *dev)
 	    dev_priv->fbc.y == crtc->y)
 		return;
 
-	if (intel_fbc_enabled(dev)) {
+	if (intel_fbc_enabled(dev) || dev_priv->fbc.plane != -1) {
 		/* We update FBC along two paths, after changing fb/crtc
 		 * configuration (modeswitching) and after page-flipping
 		 * finishes. For the latter, we know that not only did
-- 
1.8.3.2

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