From: Robert Foss <robert.foss@xxxxxxxxxxxxx>
As per the documentation in drm_crtc.h, 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@xxxxxxxxxxxxx>
---
Changes since v1:
- Corrected and simplified patch to piggyback on a previously existing check.
drivers/gpu/drm/vc4/vc4_kms.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index 4718ae5..7c7188d 100644
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -117,10 +117,18 @@ static int vc4_atomic_commit(struct drm_device *dev,
return -ENOMEM;
/* Make sure that any outstanding modesets have finished. */
- ret = down_interruptible(&vc4->async_modeset);
- if (ret) {
- kfree(c);
- return ret;
+ if (async) {
+ ret = down_trylock(&vc4->async_modeset);
+ if (ret) {
+ kfree(c);
+ return -EBUSY;
+ }
+ } else {
+ ret = down_interruptible(&vc4->async_modeset);
+ if (ret) {
+ kfree(c);
+ return ret;
+ }
}
ret = drm_atomic_helper_prepare_planes(dev, state);
--
2.5.0
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