drm/i915: Finish page flips and update primary planes after a GPU reset

GPU reset will drop all flips that are still in the ring. So after the
reset, call update_plane() for all CRTCs to make sure the primary
planes are scanning out from the correct buffer.

Also finish all pending flips. That means user space will get its
page flip events and won't get stuck waiting for them.

v2: Explicitly finish page flips instead of relying on FLIP_DONE
    interrupt being generated by the base address update.
v3: Make two loops over crtcs to avoid deadlocks with the crtc mutex
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: Fixup long line complaint from checkpatch.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_irq.c

@@ -915,6 +915,8 @@ static void i915_error_work_func(struct work_struct *work)
 		for_each_ring(ring, dev_priv, i)
 			wake_up_all(&ring->irq_queue);
 
+		intel_display_handle_reset(dev);
+
 		wake_up_all(&dev_priv->gpu_error.reset_queue);
 	}
 }

drivers/gpu/drm/i915/intel_display.c

@@ -2218,6 +2218,44 @@ intel_pipe_set_base_atomic(struct drm_crtc *crtc, struct drm_framebuffer *fb,
 	return dev_priv->display.update_plane(crtc, fb, x, y);
 }
 
+void intel_display_handle_reset(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_crtc *crtc;
+
+	/*
+	 * Flips in the rings have been nuked by the reset,
+	 * so complete all pending flips so that user space
+	 * will get its events and not get stuck.
+	 *
+	 * Also update the base address of all primary
+	 * planes to the the last fb to make sure we're
+	 * showing the correct fb after a reset.
+	 *
+	 * Need to make two loops over the crtcs so that we
+	 * don't try to grab a crtc mutex before the
+	 * pending_flip_queue really got woken up.
+	 */
+
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+		enum plane plane = intel_crtc->plane;
+
+		intel_prepare_page_flip(dev, plane);
+		intel_finish_page_flip_plane(dev, plane);
+	}
+
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+
+		mutex_lock(&crtc->mutex);
+		if (intel_crtc->active)
+			dev_priv->display.update_plane(crtc, crtc->fb,
+						       crtc->x, crtc->y);
+		mutex_unlock(&crtc->mutex);
+	}
+}
+
 static int
 intel_finish_fb(struct drm_framebuffer *old_fb)
 {

drivers/gpu/drm/i915/intel_drv.h

@@ -695,4 +695,6 @@ extern bool
 intel_ddi_connector_get_hw_state(struct intel_connector *intel_connector);
 extern void intel_ddi_fdi_disable(struct drm_crtc *crtc);
 
+extern void intel_display_handle_reset(struct drm_device *dev);
+
 #endif /* __INTEL_DRV_H__ */