| Message ID | 20180510064113.4369-1-m.szyprowski@samsung.com |
|---|---|
| State | Accepted |
| Commit | aa2f80e752c75e593b3820f42c416ed9458fa73e |
| Headers | show |
| Series | serial: samsung: fix maxburst parameter for DMA transactions | expand |
On Thu, May 10, 2018 at 08:41:13AM +0200, Marek Szyprowski wrote: > 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> > --- > drivers/tty/serial/samsung.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > Acked-by: Krzysztof Kozlowski <krzk@kernel.org> Best regards, Krzysztof -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c index 3f2f8c118ce0..64e96926f1ad 100644 --- 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");
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> --- drivers/tty/serial/samsung.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) -- 2.17.0 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html