On Mon, 2 Jul 2018 10:37:22 +0200 Daniel Vetter daniel@ffwll.ch wrote:
On Mon, Jul 02, 2018 at 10:14:51AM +0200, Boris Brezillon wrote:
On Mon, 2 Jul 2018 10:02:52 +0200 Daniel Vetter daniel@ffwll.ch wrote:
On Fri, Jun 29, 2018 at 01:17:17PM +0200, Boris Brezillon wrote:
In some cases CRTCs are active but are not able to generating events, at least not at every frame at it's expected to. This is typically the case when the CRTC is feeding a writeback connector that has no job queued. In this situation the CRTC is usually stopped until a new job is queued, and this can lead to timeouts when part of the pipeline is updated but no new jobs are queued to the active writeback connector.
In order to solve that, we add a ->no_vblank flag to drm_crtc_state and ask the CRTC drivers to set it to true when they know they're not able to generate VBLANK events. The core drm_atomic_helper_fake_vblank() helper can then be used to fake VBLANKs at commit time.
Signed-off-by: Boris Brezillon boris.brezillon@bootlin.com
drivers/gpu/drm/drm_atomic_helper.c | 40 +++++++++++++++++++++++++++++++++++++ include/drm/drm_atomic_helper.h | 1 + include/drm/drm_crtc.h | 15 ++++++++++++++ 3 files changed, 56 insertions(+)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 69063bcf2334..ca586993c2a2 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -2051,6 +2051,46 @@ void drm_atomic_helper_wait_for_dependencies(struct drm_atomic_state *old_state) } EXPORT_SYMBOL(drm_atomic_helper_wait_for_dependencies);
+/**
- drm_atomic_helper_fake_vblank - fake VBLANK events if needed
- @old_state: atomic state object with old state structures
- This function walks all CRTCs and fake VBLANK events on those with
- &drm_crtc_state.no_vblank set to true and &drm_crtc_state.event != NULL.
- The primary use of this function is writeback connectors working in oneshot
- mode and faking VBLANK events. In this case they only fake the VBLANK event
- when a job is queued, and any change to the pipeline that does not touch the
- connector is leading to timeouts when calling
- drm_atomic_helper_wait_for_vblanks() or
- drm_atomic_helper_wait_for_flip_done().
- This is part of the atomic helper support for nonblocking commits, see
- drm_atomic_helper_setup_commit() for an overview.
- */
+void drm_atomic_helper_fake_vblank(struct drm_atomic_state *old_state) +{
- struct drm_crtc_state *old_crtc_state, *new_crtc_state;
- struct drm_crtc *crtc;
- int i;
- for_each_oldnew_crtc_in_state(old_state, crtc, old_crtc_state,
new_crtc_state, i) {unsigned long flags;if (!new_crtc_state->no_vblank && !old_crtc_state->no_vblank)Uh, this essentially makes it impossible to reset no_vblank.
I don't want ->no_vblank to be reset by the core. It's up to the CRTC driver to clear/set it when something changes in the pipeline.
For control flow state bits we only check the new state for it (see e.g. the various *_changed or plane_bits or whatever).
I tried with !new_crtc_state->no_vblank only, but then it does not handle the case where the CRTC and connector are being disabled, and I end up with a timeout.
Why that? You should have a new_crtc_state even when you disable the crtc, and you can set the ->no_vblank on that one too.
Hm, right. I'll have to check why I didn't have ->no_blank set to true when I disable the CRTC. Probably a problem in vc4_crtc.c.