serial: samsung: fix maxburst parameter for DMA transactions

commit aa2f80e752c75e593b3820f42c416ed9458fa73e upstream.

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: 62c37eedb74c ("serial: samsung: add dma reqest/release functions")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index bedd4bdec4ab972b9bd323f0c2d3d806811c22f6..57baa84ccf865da0b9bd4b8571b787734f19a0ab 100644 (file)
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -865,15 +865,12 @@ 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");