4.17-stable review patch. If anyone has any objections, please let me know.
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From: Marek Szyprowski m.szyprowski@samsung.com
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
--- 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 @@ -862,15 +862,12 @@ 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->rx_chan = dma_request_chan(p->port.dev, "rx");