drm/i915: Avoid pageflipping freeze when we miss the flip prepare interrupt

When we miss the flip prepare interrupt, we never get into the
software state needed to restart userspace, resulting in a freeze of a
full-screen OpenGL application (such as a compositor).

Work around this by checking DSPxSURF/DSPxBASE to see if the page flip
has actually happened. If it has, do the work we would have done when
the flip prepare interrupt comes in.

Also, add debugfs information to tell us what's going on (based on the
patch from Chris Wilson attached to bugs.fdo bug #29798).

Signed-off-by: Simon Farnsworth <simon.farnsworth@onelan.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 0e92aa07b38..ad312ca6b3e 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -176,6 +176,16 @@ struct intel_crtc {
 #define enc_to_intel_encoder(x) container_of(x, struct intel_encoder, enc)
 #define to_intel_framebuffer(x) container_of(x, struct intel_framebuffer, base)
 
+struct intel_unpin_work {
+	struct work_struct work;
+	struct drm_device *dev;
+	struct drm_gem_object *old_fb_obj;
+	struct drm_gem_object *pending_flip_obj;
+	struct drm_pending_vblank_event *event;
+	int pending;
+	bool enable_stall_check;
+};
+
 struct i2c_adapter *intel_i2c_create(struct drm_device *dev, const u32 reg,
 				     const char *name);
 void intel_i2c_destroy(struct i2c_adapter *adapter);