[PATCH 1/2] tty: serial: samsung: pause the RX DMA channel in stop_rx

[Samarth Narang]

In s3c24xx_serial_stop_rx(), the driver pauses dma->tx_chan before
reading the residue of the RX transfer on dma->rx_chan to determine how
many bytes have been received. Since pausing the TX channel does not
stop RX DMA, additional bytes may arrive before the RX channel is
terminated, causing them to be omitted from the data passed to the tty.
This also unnecessarily pauses an active TX transfer, which the driver
does not subsequently resume.

Pause the RX channel instead, following the existing handling in
s3c24xx_serial_rx_chars_dma() on the RX timeout path.

Fixes: b543c301c2c5 ("serial: samsung: add DMA support for RX")
Link: https://lore.kernel.org/r/20261030162334.3000737-1-samarth.colleges@xxxxxxxxx
Assisted-by: LLM
Signed-off-by: Samarth Narang <samarth.colleges@xxxxxxxxx>
---
 drivers/tty/serial/samsung_tty.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index 4eeef149b..2f6c69bec 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -553,7 +553,7 @@ static void s3c24xx_serial_stop_rx(struct uart_port *port)
 		ourport->rx_enabled = 0;
 	}
 	if (dma && dma->rx_chan) {
-		dmaengine_pause(dma->tx_chan);
+		dmaengine_pause(dma->rx_chan);
 		dma_status = dmaengine_tx_status(dma->rx_chan,
 				dma->rx_cookie, &state);
 		if (dma_status == DMA_IN_PROGRESS ||
-- 
2.34.1