[PATCH 3.16 091/148] tty: serial: imx: use the sg count from dma_map_sg

[Ben Hutchings]

3.16.82-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Peng Fan <peng.fan@xxxxxxx>

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@xxxxxxx>
Link: https://lore.kernel.org/r/1573108875-26530-1-git-send-email-peng.fan@xxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/tty/serial/imx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -541,7 +541,7 @@ static void imx_dma_tx(struct imx_port *
 		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) {
 		dev_err(dev, "We cannot prepare for the TX slave dma!\n");