drm/i915/fbc: fix the FBC state checking code

We'll now call intel_fbc_pre_update instead of intel_fbc_deactivate
during atomic commits. This will continue to guarantee that we
deactivate FBC and it will also update the state checking structures
at the correct time. Then, later, at the point where we were calling
intel_fbc_update, we'll only need to call intel_fbc_post_update.

Also add the proper warnings in case we don't have the appropriate
locks. Daniel mentioned the warnings will have to be removed for async
commits, but let's keep them here while we can.
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1453210558-7875-12-git-send-email-paulo.r.zanoni@intel.com

drivers/gpu/drm/i915/intel_display.c

@@ -4799,7 +4799,7 @@ static void intel_post_plane_update(struct intel_crtc *crtc)
 		intel_update_watermarks(&crtc->base);
 
 	if (atomic->update_fbc)
-		intel_fbc_update(crtc);
+		intel_fbc_post_update(crtc);
 
 	if (atomic->post_enable_primary)
 		intel_post_enable_primary(&crtc->base);
@@ -4815,8 +4815,8 @@ static void intel_pre_plane_update(struct intel_crtc *crtc)
 	struct intel_crtc_state *pipe_config =
 		to_intel_crtc_state(crtc->base.state);
 
-	if (atomic->disable_fbc)
-		intel_fbc_deactivate(crtc);
+	if (atomic->update_fbc)
+		intel_fbc_pre_update(crtc);
 
 	if (crtc->atomic.disable_ips)
 		hsw_disable_ips(crtc);
@@ -10912,7 +10912,7 @@ static void intel_unpin_work_fn(struct work_struct *__work)
 	mutex_unlock(&dev->struct_mutex);
 
 	intel_frontbuffer_flip_complete(dev, to_intel_plane(primary)->frontbuffer_bit);
-	intel_fbc_update(crtc);
+	intel_fbc_post_update(crtc);
 	drm_framebuffer_unreference(work->old_fb);
 
 	BUG_ON(atomic_read(&crtc->unpin_work_count) == 0);
@@ -11712,7 +11712,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 			  to_intel_plane(primary)->frontbuffer_bit);
 	mutex_unlock(&dev->struct_mutex);
 
-	intel_fbc_deactivate(intel_crtc);
+	intel_fbc_pre_update(intel_crtc);
 	intel_frontbuffer_flip_prepare(dev,
 				       to_intel_plane(primary)->frontbuffer_bit);
 
@@ -11901,7 +11901,6 @@ int intel_plane_atomic_calc_changes(struct drm_crtc_state *crtc_state,
 	case DRM_PLANE_TYPE_PRIMARY:
 		intel_crtc->atomic.pre_disable_primary = turn_off;
 		intel_crtc->atomic.post_enable_primary = turn_on;
-		intel_crtc->atomic.disable_fbc = true;
 		intel_crtc->atomic.update_fbc = true;
 
 		if (turn_off) {

drivers/gpu/drm/i915/intel_drv.h

@@ -542,16 +542,17 @@ struct intel_mmio_flip {
  */
 struct intel_crtc_atomic_commit {
 	/* Sleepable operations to perform before commit */
-	bool disable_fbc;
 	bool disable_ips;
 	bool pre_disable_primary;
 
 	/* Sleepable operations to perform after commit */
 	unsigned fb_bits;
 	bool wait_vblank;
-	bool update_fbc;
 	bool post_enable_primary;
 	unsigned update_sprite_watermarks;
+
+	/* Sleepable operations to perform before and after commit */
+	bool update_fbc;
 };
 
 struct intel_crtc {
@@ -1330,7 +1331,8 @@ static inline void intel_fbdev_restore_mode(struct drm_device *dev)
 /* intel_fbc.c */
 bool intel_fbc_is_active(struct drm_i915_private *dev_priv);
 void intel_fbc_deactivate(struct intel_crtc *crtc);
-void intel_fbc_update(struct intel_crtc *crtc);
+void intel_fbc_pre_update(struct intel_crtc *crtc);
+void intel_fbc_post_update(struct intel_crtc *crtc);
 void intel_fbc_init(struct drm_i915_private *dev_priv);
 void intel_fbc_enable(struct intel_crtc *crtc);
 void intel_fbc_disable(struct drm_i915_private *dev_priv);

drivers/gpu/drm/i915/intel_fbc.c

@@ -510,6 +510,7 @@ static bool multiple_pipes_ok(struct drm_i915_private *dev_priv)
 	if (INTEL_INFO(dev_priv)->gen > 4)
 		return true;
 
+	/* FIXME: we don't have the appropriate state locks to do this here. */
 	for_each_pipe(dev_priv, pipe) {
 		crtc = dev_priv->pipe_to_crtc_mapping[pipe];
 
@@ -732,12 +733,16 @@ static void intel_fbc_update_state_cache(struct intel_crtc *crtc)
 	struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
 	struct intel_fbc *fbc = &dev_priv->fbc;
 	struct intel_fbc_state_cache *cache = &fbc->state_cache;
-	struct intel_crtc_state *crtc_state = crtc->config;
+	struct intel_crtc_state *crtc_state =
+		to_intel_crtc_state(crtc->base.state);
 	struct intel_plane_state *plane_state =
 		to_intel_plane_state(crtc->base.primary->state);
 	struct drm_framebuffer *fb = plane_state->base.fb;
 	struct drm_i915_gem_object *obj;
 
+	WARN_ON(!drm_modeset_is_locked(&crtc->base.mutex));
+	WARN_ON(!drm_modeset_is_locked(&crtc->base.primary->mutex));
+
 	cache->crtc.mode_flags = crtc_state->base.adjusted_mode.flags;
 	if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv))
 		cache->crtc.hsw_bdw_pixel_rate =
@@ -896,12 +901,15 @@ static bool intel_fbc_reg_params_equal(struct intel_fbc_reg_params *params1,
 	return memcmp(params1, params2, sizeof(*params1)) == 0;
 }
 
-static void intel_fbc_pre_update(struct intel_crtc *crtc)
+void intel_fbc_pre_update(struct intel_crtc *crtc)
 {
 	struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
 	struct intel_fbc *fbc = &dev_priv->fbc;
 
-	WARN_ON(!mutex_is_locked(&fbc->lock));
+	if (!fbc_supported(dev_priv))
+		return;
+
+	mutex_lock(&fbc->lock);
 
 	if (!multiple_pipes_ok(dev_priv)) {
 		set_no_fbc_reason(dev_priv, "more than one pipe active");
@@ -909,15 +917,17 @@ static void intel_fbc_pre_update(struct intel_crtc *crtc)
 	}
 
 	if (!fbc->enabled || fbc->crtc != crtc)
-		return;
+		goto unlock;
 
 	intel_fbc_update_state_cache(crtc);
 
 deactivate:
 	__intel_fbc_deactivate(dev_priv);
+unlock:
+	mutex_unlock(&fbc->lock);
 }
 
-static void intel_fbc_post_update(struct intel_crtc *crtc)
+static void __intel_fbc_post_update(struct intel_crtc *crtc)
 {
 	struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
 	struct intel_fbc *fbc = &dev_priv->fbc;
@@ -950,13 +960,7 @@ static void intel_fbc_post_update(struct intel_crtc *crtc)
 	fbc->no_fbc_reason = "FBC enabled (active or scheduled)";
 }
 
-/*
- * intel_fbc_update - activate/deactivate FBC as needed
- * @crtc: the CRTC that triggered the update
- *
- * This function reevaluates the overall state and activates or deactivates FBC.
- */
-void intel_fbc_update(struct intel_crtc *crtc)
+void intel_fbc_post_update(struct intel_crtc *crtc)
 {
 	struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
 	struct intel_fbc *fbc = &dev_priv->fbc;
@@ -965,8 +969,7 @@ void intel_fbc_update(struct intel_crtc *crtc)
 		return;
 
 	mutex_lock(&fbc->lock);
-	intel_fbc_pre_update(crtc);
-	intel_fbc_post_update(crtc);
+	__intel_fbc_post_update(crtc);
 	mutex_unlock(&fbc->lock);
 }
 
@@ -1020,7 +1023,7 @@ void intel_fbc_flush(struct drm_i915_private *dev_priv,
 		if (fbc->active)
 			intel_fbc_recompress(dev_priv);
 		else
-			intel_fbc_post_update(fbc->crtc);
+			__intel_fbc_post_update(fbc->crtc);
 	}
 
 	mutex_unlock(&fbc->lock);