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 f2ab6d8..5609305 100644 (file)
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -866,15 +866,12 @@ 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_cap_zero(mask);
        dma_cap_set(DMA_SLAVE, mask);