[PATCH v2 01/13] dmaengine: ste_dma40: Fix failed start cleanup

[Linus Walleij <linusw@kernel.org>]

If d40_start() fails after a queued descriptor has been moved to the
active list, d40_queue_start() currently returns NULL without unwinding
the transfer state or clearing the channel busy flag.

Fix this pre-existing error path by completing the descriptor through the
normal tasklet path, clearing the busy flag, balancing the runtime PM
reference and returning an error pointer to distinguish the failure from
the no-work case. Do not free the descriptor directly, since it has
already been submitted and has a DMA cookie.

Reported-by: sashiko-bot@kernel.org
Closes: https://lore.kernel.org/dmaengine/20260618051539.15E201F000E9@smtp.kernel.org/
Assisted-by: Codex:gpt-5-5
Signed-off-by: Linus Walleij <linusw@kernel.org>
---
 drivers/dma/ste_dma40.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
index 0d9ffa3e2663..facc1bcf42a0 100644
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -1531,8 +1531,15 @@ static struct d40_desc *d40_queue_start(struct d40_chan *d40c)
 		/* Start dma job */
 		err = d40_start(d40c);
 
-		if (err)
-			return NULL;
+		if (err) {
+			d40_desc_remove(d40d);
+			d40_desc_done(d40c, d40d);
+			d40c->pending_tx++;
+			d40c->busy = false;
+			pm_runtime_put_autosuspend(d40c->base->dev);
+			tasklet_schedule(&d40c->tasklet);
+			return ERR_PTR(err);
+		}
 	}
 
 	return d40d;

-- 
2.55.0