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serial: samsung: fix maxburst parameter for DMA transactions

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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: 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>
This commit is contained in:
Marek Szyprowski 2018-05-10 08:41:13 +02:00 • committed by Greg Kroah-Hartman
parent 326908105f
commit 6ffaa6e0f3
1 changed files with 2 additions and 5 deletions
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7
drivers/tty/serial/samsung.c
View file

@ -860,15 +860,12 @@ static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
dma->rx_conf.direction = DMA_DEV_TO_MEM; dma->rx_conf.direction = DMA_DEV_TO_MEM;
dma->rx_conf.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; 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_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.direction = DMA_MEM_TO_DEV;
dma->tx_conf.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; dma->tx_conf.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
dma->tx_conf.dst_addr = p->port.mapbase + S3C2410_UTXH; dma->tx_conf.dst_addr = p->port.mapbase + S3C2410_UTXH;
if (dma_get_cache_alignment() >= 16) dma->tx_conf.dst_maxburst = 1;
dma->tx_conf.dst_maxburst = 16;
else
dma->tx_conf.dst_maxburst = 1;
dma_cap_zero(mask); dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask); dma_cap_set(DMA_SLAVE, mask);