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serial: samsung: fix maxburst parameter for DMA transactions 

commit aa2f80e752 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: 62c37eedb7 ("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>
pull/10/head
Marek Szyprowski 2018-05-10 08:41:13 +02:00 committed by Greg Kroah-Hartman
parent db30b8eb96
commit 804f090110
1 changed files with 2 additions and 5 deletions
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7
drivers/tty/serial/samsung.c
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@ -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");