omap_crtc_flush() is used to wait for scheduled work to be done for the
give crtc. However, it's not quite right at the moment.
omap_crtc_flush() does wait for work that is ran via vsync irq to be
done. However, work is also queued to the driver's priv->wq workqueue,
which is not handled by omap_crtc_flush().
Improve omap_crtc_flush() to flush the workqueue so that work there will
be ran.
This fixes a race issue on module unload, where an unpin work may be on
the work queue, but does not get ran before drm core starts tearing the
driver down, leading to a WARN.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
---
drivers/gpu/drm/omapdrm/omap_crtc.c | 31 ++++++++++++++++++++++++++-----
1 file changed, 26 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/omapdrm/omap_crtc.c b/drivers/gpu/drm/omapdrm/omap_crtc.c
index 3261fbf94957..506cf8bc804f 100644
--- a/drivers/gpu/drm/omapdrm/omap_crtc.c
+++ b/drivers/gpu/drm/omapdrm/omap_crtc.c
@@ -655,21 +655,42 @@ static void omap_crtc_post_apply(struct omap_drm_apply *apply)
/* nothing needed for post-apply */
}
+static bool omap_crtc_work_pending(struct omap_crtc *omap_crtc)
+{
+ return !list_empty(&omap_crtc->pending_applies) ||
+ !list_empty(&omap_crtc->queued_applies) ||
+ omap_crtc->event || omap_crtc->old_fb;
+}
+
+/*
+ * Wait for any work on the workqueue to be finished, and any work which will
+ * be run via vsync irq to be done.
+ *
+ * Note that work on workqueue could schedule new vsync work, and vice versa.
+ */
void omap_crtc_flush(struct drm_crtc *crtc)
{
struct omap_crtc *omap_crtc = to_omap_crtc(crtc);
+ struct omap_drm_private *priv = crtc->dev->dev_private;
int loops = 0;
- while (!list_empty(&omap_crtc->pending_applies) ||
- !list_empty(&omap_crtc->queued_applies) ||
- omap_crtc->event || omap_crtc->old_fb) {
+ while (true) {
+ /* first flush the wq, so that any scheduled work is done */
+ flush_workqueue(priv->wq);
+
+ /* if we have nothing queued for this crtc, we're done */
+ if (!omap_crtc_work_pending(omap_crtc))
+ break;
if (++loops > 10) {
- dev_err(crtc->dev->dev,
- "omap_crtc_flush() timeout\n");
+ dev_err(crtc->dev->dev, "omap_crtc_flush() timeout\n");
break;
}
+ /*
+ * wait for a bit so that a vsync has (probably) happened, and
+ * that the crtc work is (probably) done.
+ */
schedule_timeout_uninterruptible(msecs_to_jiffies(20));
}
}
--
1.9.1
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