robert.foss@collabora.com writes:
From: Robert Foss robert.foss@collabora.com
As per the docs, atomic_commit should return -EBUSY "if an asycnhronous update is requested and there is an earlier update pending".
Note: docs cited here are drm_crtc.h, and the whole quote is:
* - -EBUSY, if an asynchronous updated is requested and there is * an earlier updated pending. Drivers are allowed to support a queue * of outstanding updates, but currently no driver supports that. * Note that drivers must wait for preceding updates to complete if a * synchronous update is requested, they are not allowed to fail the * commit in that case.
Signed-off-by: Robert Foss robert.foss@collabora.com
drivers/gpu/drm/vc4/vc4_crtc.c | 6 ++++++ drivers/gpu/drm/vc4/vc4_drv.h | 1 + drivers/gpu/drm/vc4/vc4_kms.c | 20 ++++++++++++++++++-- 3 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c index 355ee4b..43193a3 100644 --- a/drivers/gpu/drm/vc4/vc4_crtc.c +++ b/drivers/gpu/drm/vc4/vc4_crtc.c @@ -802,3 +802,9 @@ struct platform_driver vc4_crtc_driver = { .of_match_table = vc4_crtc_dt_match, }, };
+bool vc4_crtc_has_pending_event(struct drm_crtc *crtc) +{
- assert_spin_locked(&crtc->dev->event_lock);
- return to_vc4_crtc(crtc)->event;
+} diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h index fa2ad15..54c1fb5 100644 --- a/drivers/gpu/drm/vc4/vc4_drv.h +++ b/drivers/gpu/drm/vc4/vc4_drv.h @@ -414,6 +414,7 @@ extern struct platform_driver vc4_crtc_driver; int vc4_enable_vblank(struct drm_device *dev, unsigned int crtc_id); void vc4_disable_vblank(struct drm_device *dev, unsigned int crtc_id); int vc4_crtc_debugfs_regs(struct seq_file *m, void *arg); +bool vc4_crtc_has_pending_event(struct drm_crtc *crtc);
/* vc4_debugfs.c */ int vc4_debugfs_init(struct drm_minor *minor); diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c index 4718ae5..dc157a1e 100644 --- a/drivers/gpu/drm/vc4/vc4_kms.c +++ b/drivers/gpu/drm/vc4/vc4_kms.c @@ -107,10 +107,26 @@ static int vc4_atomic_commit(struct drm_device *dev, bool async) { struct vc4_dev *vc4 = to_vc4_dev(dev);
- int ret;
- int i; uint64_t wait_seqno = 0; struct vc4_commit *c;
- struct drm_crtc_state *crtc_state;
- struct drm_crtc *crtc;
- unsigned long flags;
- int i, ret;
- if (async) {
for_each_crtc_in_state(state, crtc, crtc_state, i) {spin_lock_irqsave(&dev->event_lock, flags);if (crtc->state->event ||vc4_crtc_has_pending_event(crtc)) {spin_unlock_irqrestore(&dev->event_lock, flags);return -EBUSY;}spin_unlock_irqrestore(&dev->event_lock, flags);}- }
By my reading, the point of returning -EBUSY here is just to avoid blocking when the compositor asked for nonblocking. You're checking that each CRTC involved in the commit doesn't have a queued pageflip event, except that then we immediately proceed to:
/* Make sure that any outstanding modesets have finished. */ ret = down_interruptible(&vc4->async_modeset); if (ret) { kfree(c); return ret; }
so this per-CRTC check doesn't prevent blocking if the set of CRTCs for this commit was disjoint from the last one, right? To implement the minimal behavior, I think we'd want to just down_trylock instead in the async case, I think. And to implement the disjoint CRTC thing you were trying for, I think we'd need to track a mask kind of like msm's pending_crtcs.