[PATCH] dmaengine: mediatek: uart: clear the active descriptor on termination

[James Hilliard]

mtk_uart_apdma_issue_pending() keeps the active descriptor in desc_issued
and stores an alias in c->desc. Terminating the channel collects and frees
that list, but leaves c->desc pointing at the retired descriptor unless
the completion interrupt has already cleared it.

The next issue_pending() requires c->desc to be NULL before starting a
transfer. Canceling an active transfer can therefore leave the channel
unable to start subsequent transfers, even after synchronization.

Clear c->desc under the virtual-channel lock when collecting the terminated
descriptors, after the existing interrupt shutdown and synchronization.

Fixes: 2537b40b0a4f ("dmaengine: mediatek: do not issue a new desc if one is still current")
Cc: stable at vger.kernel.org
Signed-off-by: James Hilliard <james.hilliard1 at gmail.com>
---
 drivers/dma/mediatek/mtk-uart-apdma.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/dma/mediatek/mtk-uart-apdma.c b/drivers/dma/mediatek/mtk-uart-apdma.c
index f74e9a328588..d9427d56bc50 100644
--- a/drivers/dma/mediatek/mtk-uart-apdma.c
+++ b/drivers/dma/mediatek/mtk-uart-apdma.c
@@ -433,6 +433,7 @@ static int mtk_uart_apdma_terminate_all(struct dma_chan *chan)
 
 	spin_lock_irqsave(&c->vc.lock, flags);
 	vchan_get_all_descriptors(&c->vc, &head);
+	c->desc = NULL;
 	spin_unlock_irqrestore(&c->vc.lock, flags);
 
 	vchan_dma_desc_free_list(&c->vc, &head);

---
base-commit: 93f51579e7df248780214094418f205253383cc5
change-id: 20261022-submit-mtk-uart-dma-retire-v1-fe71753c51ff

Best regards,
--  
James Hilliard <james.hilliard1 at gmail.com>