drm/i915: Clear FlipDone semantics change for pageflipping on gen3

On later gen3, you are able to select the meaning of the FlipPending
status bit in IIR and change it to FlipDone. This was sometimes done by
the BIOS leading to confusion on just how pageflipping worked on gen3.
Simplify the implementation by using the legacy meaning for all gen3
machines.

Note: this makes all gen3 machines equally broken...

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -748,7 +748,6 @@ typedef struct drm_i915_private {
 	struct drm_crtc *plane_to_crtc_mapping[3];
 	struct drm_crtc *pipe_to_crtc_mapping[3];
 	wait_queue_head_t pending_flip_queue;
-	bool gen3_flip_pending_is_done;
 
 	struct intel_pch_pll pch_plls[I915_NUM_PLLS];
 

drivers/gpu/drm/i915/i915_irq.c

@@ -2510,26 +2510,18 @@ static irqreturn_t i915_irq_handler(DRM_IRQ_ARGS)
 		if (iir & I915_BSD_USER_INTERRUPT)
 			notify_ring(dev, &dev_priv->ring[VCS]);
 
-		if (iir & I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT) {
+		if (iir & I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT)
 			intel_prepare_page_flip(dev, 0);
-			if (dev_priv->gen3_flip_pending_is_done)
-				intel_finish_page_flip_plane(dev, 0);
-		}
 
-		if (iir & I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT) {
+		if (iir & I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT)
 			intel_prepare_page_flip(dev, 1);
-			if (dev_priv->gen3_flip_pending_is_done)
-				intel_finish_page_flip_plane(dev, 1);
-		}
 
 		for_each_pipe(pipe) {
 			if (pipe_stats[pipe] & vblank_status &&
 			    drm_handle_vblank(dev, pipe)) {
 				vblank++;
-				if (!dev_priv->gen3_flip_pending_is_done) {
-					i915_pageflip_stall_check(dev, pipe);
-					intel_finish_page_flip(dev, pipe);
-				}
+				i915_pageflip_stall_check(dev, pipe);
+				intel_finish_page_flip(dev, pipe);
 			}
 
 			if (pipe_stats[pipe] & PIPE_LEGACY_BLC_EVENT_STATUS)
@@ -2771,26 +2763,18 @@ static irqreturn_t i965_irq_handler(DRM_IRQ_ARGS)
 		if (iir & I915_BSD_USER_INTERRUPT)
 			notify_ring(dev, &dev_priv->ring[VCS]);
 
-		if (iir & I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT) {
+		if (iir & I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT)
 			intel_prepare_page_flip(dev, 0);
-			if (dev_priv->gen3_flip_pending_is_done)
-				intel_finish_page_flip_plane(dev, 0);
-		}
 
-		if (iir & I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT) {
+		if (iir & I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT)
 			intel_prepare_page_flip(dev, 1);
-			if (dev_priv->gen3_flip_pending_is_done)
-				intel_finish_page_flip_plane(dev, 1);
-		}
 
 		for_each_pipe(pipe) {
 			if (pipe_stats[pipe] & vblank_status &&
 			    drm_handle_vblank(dev, pipe)) {
 				vblank++;
-				if (!dev_priv->gen3_flip_pending_is_done) {
-					i915_pageflip_stall_check(dev, pipe);
-					intel_finish_page_flip(dev, pipe);
-				}
+				i915_pageflip_stall_check(dev, pipe);
+				intel_finish_page_flip(dev, pipe);
 			}
 
 			if (pipe_stats[pipe] & PIPE_LEGACY_BLC_EVENT_STATUS)
@@ -2857,10 +2841,6 @@ void intel_irq_init(struct drm_device *dev)
 	INIT_WORK(&dev_priv->error_work, i915_error_work_func);
 	INIT_WORK(&dev_priv->rps_work, gen6_pm_rps_work);
 
-	/* IIR "flip pending" bit means done if this bit is set */
-	if (IS_GEN3(dev) && (I915_READ(ECOSKPD) & ECO_FLIP_DONE))
-		dev_priv->gen3_flip_pending_is_done = true;
-
 	dev->driver->get_vblank_counter = i915_get_vblank_counter;
 	dev->max_vblank_count = 0xffffff; /* only 24 bits of frame count */
 	if (IS_G4X(dev) || IS_GEN5(dev) || IS_GEN6(dev) || IS_IVYBRIDGE(dev) ||
@@ -2904,6 +2884,9 @@ void intel_irq_init(struct drm_device *dev)
 			dev->driver->irq_handler = i8xx_irq_handler;
 			dev->driver->irq_uninstall = i8xx_irq_uninstall;
 		} else if (INTEL_INFO(dev)->gen == 3) {
+			/* IIR "flip pending" means done if this bit is set */
+			I915_WRITE(ECOSKPD, _MASKED_BIT_DISABLE(ECO_FLIP_DONE));
+
 			dev->driver->irq_preinstall = i915_irq_preinstall;
 			dev->driver->irq_postinstall = i915_irq_postinstall;
 			dev->driver->irq_uninstall = i915_irq_uninstall;