4.9-stable review patch. If anyone has any objections, please let me know.
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From: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
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@xxxxxxxxxxx>
Acked-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/samsung.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -866,15 +866,12 @@ static int s3c24xx_serial_request_dma(st
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);
