linux-kernel - [PATCH 10/15] tty: 8250_omap: use dmaengine_prep_slave

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Date: Fri,  5 Apr 2024 08:08:21 +0200
From: "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
To: gregkh@...uxfoundation.org
Cc: linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Jiri Slaby (SUSE)" <jirislaby@...nel.org>
Subject: [PATCH 10/15] tty: 8250_omap: use dmaengine_prep_slave_sg()

This is a preparatory for the serial-to-kfifo switch. kfifo understands
only scatter-gatter approach, so switch to that.

No functional change intended, it's just dmaengine_prep_slave_single()
inline expanded.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@...nel.org>
---
 drivers/tty/serial/8250/8250_omap.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 66901d93089a..879e77b30701 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -1140,6 +1140,7 @@ static int omap_8250_tx_dma(struct uart_8250_port *p)
 	struct omap8250_priv		*priv = p->port.private_data;
 	struct circ_buf			*xmit = &p->port.state->xmit;
 	struct dma_async_tx_descriptor	*desc;
+	struct scatterlist sg;
 	unsigned int	skip_byte = 0;
 	int ret;
 
@@ -1191,9 +1192,11 @@ static int omap_8250_tx_dma(struct uart_8250_port *p)
 		skip_byte = 1;
 	}
 
-	desc = dmaengine_prep_slave_single(dma->txchan,
-			dma->tx_addr + xmit->tail + skip_byte,
-			dma->tx_size - skip_byte, DMA_MEM_TO_DEV,
+	sg_init_table(&sg, 1);
+	sg_dma_address(&sg) = dma->tx_addr + xmit->tail + skip_byte;
+	sg_dma_len(&sg) = dma->tx_size - skip_byte;
+
+	desc = dmaengine_prep_slave_sg(dma->txchan, &sg, 1, DMA_MEM_TO_DEV,
 			DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	if (!desc) {
 		ret = -EBUSY;
-- 
2.44.0