tty: serial: imx: use the sg count from dma_map_sg

The dmaengine_prep_slave_sg needs to use sg count returned
by dma_map_sg, not use sport->dma_tx_nents, because the return
value of dma_map_sg is not always same with "nents".

Fixes: b4cdc8f61beb ("serial: imx: add DMA support for imx6q")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/1573108875-26530-1-git-send-email-peng.fan@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 357d3ff..a9e20e6 100644 (file)
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -619,7 +619,7 @@ static void imx_uart_dma_tx(struct imx_port *sport)
                dev_err(dev, "DMA mapping error for TX.\n");
                return;
        }
-       desc = dmaengine_prep_slave_sg(chan, sgl, sport->dma_tx_nents,
+       desc = dmaengine_prep_slave_sg(chan, sgl, ret,
                                        DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT);
        if (!desc) {
                dma_unmap_sg(dev, sgl, sport->dma_tx_nents,