[PATCH v2 1/2] dmaengine: cppi41: Fix list not empty warning on runtime suspend

[Alexandre Bailon <abailon-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>]

Sometime, a transfer may not be queued due to a race between runtime pm
and cppi41_dma_issue_pending().
Sometime, cppi41_runtime_resume() may be interrupted right before to
update device PM state to RESUMED.
When it happens, if a new dma transfer is issued, because the device is not
in active state, the descriptor will be added to the pendding list.
But because the descriptors in the pendding list are only queued to cppi41
on runtime resume, the descriptor will not be queued.
On runtime suspend, the list is not empty, which is causing a warning.
Queue the descriptor if the device is active or resuming.

Signed-off-by: Alexandre Bailon <abailon-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>
---
 drivers/dma/cppi41.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c
index d5ba43a..025fee4 100644
--- a/drivers/dma/cppi41.c
+++ b/drivers/dma/cppi41.c
@@ -471,6 +471,8 @@ static void cppi41_dma_issue_pending(struct dma_chan *chan)
 {
 	struct cppi41_channel *c = to_cpp41_chan(chan);
 	struct cppi41_dd *cdd = c->cdd;
+	unsigned long flags;
+	bool active;
 	int error;
 
 	error = pm_runtime_get(cdd->ddev.dev);
@@ -482,7 +484,21 @@ static void cppi41_dma_issue_pending(struct dma_chan *chan)
 		return;
 	}
 
-	if (likely(pm_runtime_active(cdd->ddev.dev)))
+	active = pm_runtime_active(cdd->ddev.dev);
+	if (!active) {
+		/*
+		 * Runtime resume may be interrupted before runtime_status
+		 * has been updated. Test if device has resumed.
+		 */
+		if (error == -EINPROGRESS) {
+			spin_lock_irqsave(&cdd->lock, flags);
+			if (list_empty(&cdd->pending))
+				active = true;
+			spin_unlock_irqrestore(&cdd->lock, flags);
+		}
+	}
+
+	if (likely(active))
 		push_desc_queue(c);
 	else
 		pending_desc(c);
-- 
2.10.2

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