drm/i915: Swap primary planes on gen2 for FBC

Only plane A is FBC capable on gen2 (like gen3), but the panel fitter
is hooked up to pipe B, so we want to prefer pipe B + plane A.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: Add the code comment Chris requested in his review.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_irq.c

@@ -3139,10 +3139,10 @@ static int i8xx_irq_postinstall(struct drm_device *dev)
  * Returns true when a page flip has completed.
  */
 static bool i8xx_handle_vblank(struct drm_device *dev,
-			       int pipe, u16 iir)
+			       int plane, int pipe, u32 iir)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
-	u16 flip_pending = DISPLAY_PLANE_FLIP_PENDING(pipe);
+	u16 flip_pending = DISPLAY_PLANE_FLIP_PENDING(plane);
 
 	if (!drm_handle_vblank(dev, pipe))
 		return false;
@@ -3150,7 +3150,7 @@ static bool i8xx_handle_vblank(struct drm_device *dev,
 	if ((iir & flip_pending) == 0)
 		return false;
 
-	intel_prepare_page_flip(dev, pipe);
+	intel_prepare_page_flip(dev, plane);
 
 	/* We detect FlipDone by looking for the change in PendingFlip from '1'
 	 * to '0' on the following vblank, i.e. IIR has the Pendingflip
@@ -3219,9 +3219,13 @@ static irqreturn_t i8xx_irq_handler(int irq, void *arg)
 			notify_ring(dev, &dev_priv->ring[RCS]);
 
 		for_each_pipe(pipe) {
+			int plane = pipe;
+			if (IS_MOBILE(dev))
+				plane = !plane;
+
 			if (pipe_stats[pipe] & PIPE_VBLANK_INTERRUPT_STATUS &&
-			    i8xx_handle_vblank(dev, pipe, iir))
-				flip_mask &= ~DISPLAY_PLANE_FLIP_PENDING(pipe);
+			    i8xx_handle_vblank(dev, plane, pipe, iir))
+				flip_mask &= ~DISPLAY_PLANE_FLIP_PENDING(plane);
 
 			if (pipe_stats[pipe] & PIPE_CRC_DONE_INTERRUPT_STATUS)
 				i9xx_pipe_crc_irq_handler(dev, pipe);

drivers/gpu/drm/i915/intel_display.c

@@ -10109,10 +10109,13 @@ static void intel_crtc_init(struct drm_device *dev, int pipe)
 		intel_crtc->lut_b[i] = i;
 	}
 
-	/* Swap pipes & planes for FBC on pre-965 */
+	/*
+	 * On gen2/3 only plane A can do fbc, but the panel fitter and lvds port
+	 * is hooked to plane B. Hence we want plane A feeding pipe B.
+	 */
 	intel_crtc->pipe = pipe;
 	intel_crtc->plane = pipe;
-	if (IS_MOBILE(dev) && IS_GEN3(dev)) {
+	if (IS_MOBILE(dev) && INTEL_INFO(dev)->gen < 4) {
 		DRM_DEBUG_KMS("swapping pipes & planes for FBC\n");
 		intel_crtc->plane = !pipe;
 	}