serial: samsung: fix maxburst parameter for DMA transactions

The best granularity of residue that DMA engine can report is in the BURST units, so the serial driver must use MAXBURST = 1 and DMA_SLAVE_BUSWIDTH_1_BYTE if it relies on exact number of bytes transferred by DMA engine. Fixes: 62c37ee ("serial: samsung: add dma reqest/release functions") Signed-off-by: Marek Szyprowski <[email protected]> Acked-by: Krzysztof Kozlowski <[email protected]> Cc: stable <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
JerzyD72 · May 14, 2018 · aa2f80e · aa2f80e
1 parent 2ccdb55
commit aa2f80e
Showing 1 changed file with 2 additions and 5 deletions.
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
@@ -862,15 +862,12 @@ static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
 	dma->rx_conf.direction		= DMA_DEV_TO_MEM;
 	dma->rx_conf.src_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
 	dma->rx_conf.src_addr		= p->port.mapbase + S3C2410_URXH;
-	dma->rx_conf.src_maxburst	= 16;
+	dma->rx_conf.src_maxburst	= 1;
 
 	dma->tx_conf.direction		= DMA_MEM_TO_DEV;
 	dma->tx_conf.dst_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
 	dma->tx_conf.dst_addr		= p->port.mapbase + S3C2410_UTXH;
-	if (dma_get_cache_alignment() >= 16)
-		dma->tx_conf.dst_maxburst = 16;
-	else
-		dma->tx_conf.dst_maxburst = 1;
+	dma->tx_conf.dst_maxburst	= 1;
 
 	dma->rx_chan = dma_request_chan(p->port.dev, "rx");