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

BugLink: https://bugs.launchpad.net/bugs/1861934
commit 596fd8dffb745afcebc0ec6968e17fe29f02044c upstream.

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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index b8897b024eb7935ae4efc76c37fcfa1ddf8829a7..31f0e61bef88268c809662a871cb6a91e9cb1800 100644 (file)
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -533,7 +533,7 @@ static void imx_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,