On Fri, Sep 14, 2012 at 02:57:26PM +0100, Chris Wilson wrote:
On Wed, 12 Sep 2012 18:47:07 +0300, ville.syrjala@linux.intel.com wrote:
+static void intel_flip_finish(struct drm_flip *flip) +{
- struct intel_flip *intel_flip =
container_of(flip, struct intel_flip, base);- struct drm_device *dev = intel_flip->crtc->dev;
- if (intel_flip->old_bo) {
mutex_lock(&dev->struct_mutex);intel_finish_fb(intel_flip->old_bo);So if I understand correctly, this code is called after the flip is already complete?
Yes.
The intel_finish_fb() exists to flush pending batches and flips on the current fb, prior to changing the scanout registers. (There is a hardware dependency such that the GPU may be executing a command that required the current modesetting.) In the case of flip completion, all of those dependencies have already been retired and so the finish should be a no-op. And so it should no be required, nor the changes to intel_finish_fb (which should have included a change in the name to indicate that is now taking the fb_obj).
Actually I'm not quite sure where this intel_finish_fb() call originated. Based on the name it didn't make sense to me, but I left it there for now. Hmm. OK it came from one patch from Imre while I was on vacation. I suppose he got it from intel_pipe_set_base() which does call intel_finish_fb() on the old fb. Why does it do that?
I've not really dug into the GPU synchronization side and pin/fence stuff, so it's no surprise my code is a bit fscked up in those areas.