drm/i915: fix FBC frontbuffer tracking flushing code

Due to the way busy_bits was handled, we were not doing any flushes if
we didn't previously get an invalidate. Since it's possible to get
flushes without an invalidate first, remove the busy_bits early
return.

So now that we don't have the busy_bits guard anymore we'll need the
origin check for the GTT tracking (we were not doing anything on GTT
flushes due to the GTT check at invalidate()).

As a last detail, since we can get multiple consecutive flushes,
disable FBC before updating it, otherwise intel_fbc_update() will just
keep FBC enabled instead of restarting it.

Notice that this does not fix any of the current IGT tests due to the
fact that we still have a few intel_fbc() calls at points where we
also have the frontbuffer tracking calls: we didn't fully convert to
frontbuffer tracking yet. Once we remove those calls and start relying
only on the frontbuffer tracking infrastructure we'll need this patch.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_drv.h

@@ -1239,7 +1239,7 @@ void intel_fbc_invalidate(struct drm_i915_private *dev_priv,
 			  unsigned int frontbuffer_bits,
 			  enum fb_op_origin origin);
 void intel_fbc_flush(struct drm_i915_private *dev_priv,
-		     unsigned int frontbuffer_bits);
+		     unsigned int frontbuffer_bits, enum fb_op_origin origin);
 const char *intel_no_fbc_reason_str(enum no_fbc_reason reason);
 void intel_fbc_cleanup_cfb(struct drm_i915_private *dev_priv);
 

drivers/gpu/drm/i915/intel_fbc.c

@@ -884,22 +884,23 @@ void intel_fbc_invalidate(struct drm_i915_private *dev_priv,
 }
 
 void intel_fbc_flush(struct drm_i915_private *dev_priv,
-		     unsigned int frontbuffer_bits)
+		     unsigned int frontbuffer_bits, enum fb_op_origin origin)
 {
 	if (!dev_priv->fbc.enable_fbc)
 		return;
 
-	mutex_lock(&dev_priv->fbc.lock);
+	if (origin == ORIGIN_GTT)
+		return;
 
-	if (!dev_priv->fbc.busy_bits)
-		goto out;
+	mutex_lock(&dev_priv->fbc.lock);
 
 	dev_priv->fbc.busy_bits &= ~frontbuffer_bits;
 
-	if (!dev_priv->fbc.busy_bits)
+	if (!dev_priv->fbc.busy_bits) {
+		__intel_fbc_disable(dev_priv);
 		__intel_fbc_update(dev_priv);
+	}
 
-out:
 	mutex_unlock(&dev_priv->fbc.lock);
 }
 

drivers/gpu/drm/i915/intel_frontbuffer.c

@@ -129,7 +129,7 @@ static void intel_frontbuffer_flush(struct drm_device *dev,
 
 	intel_edp_drrs_flush(dev, frontbuffer_bits);
 	intel_psr_flush(dev, frontbuffer_bits, origin);
-	intel_fbc_flush(dev_priv, frontbuffer_bits);
+	intel_fbc_flush(dev_priv, frontbuffer_bits, origin);
 }
 
 /**