On 19.04.2024 10:09, Jiri Slaby (SUSE) wrote:
> The -next commit f8fef2fa419f (tty: msm_serial: use
> dmaengine_prep_slave_sg()), switched to using dma_map_sg(). But the
> return value of dma_map_sg() is special: it returns number of elements
> mapped. And not a standard error value.
>
> The commit also forgot to reset dma->tx_sg in case of this failure.
>
> Fix both these mistakes.
>
> Thanks to Marek who helped debugging this.
>
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@xxxxxxxxxx>
> Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> ---
> drivers/tty/serial/msm_serial.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
> index ae7a8e3cf467..0a9c5219df88 100644
> --- a/drivers/tty/serial/msm_serial.c
> +++ b/drivers/tty/serial/msm_serial.c
> @@ -499,15 +499,18 @@ static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
> struct uart_port *port = &msm_port->uart;
> struct tty_port *tport = &port->state->port;
> struct msm_dma *dma = &msm_port->tx_dma;
> + unsigned int mapped;
> int ret;
> u32 val;
>
> sg_init_table(&dma->tx_sg, 1);
> kfifo_dma_out_prepare(&tport->xmit_fifo, &dma->tx_sg, 1, count);
>
> - ret = dma_map_sg(port->dev, &dma->tx_sg, 1, dma->dir);
> - if (ret)
> - return ret;
> + mapped = dma_map_sg(port->dev, &dma->tx_sg, 1, dma->dir);
> + if (!mapped) {
> + ret = -EIO;
> + goto zero_sg;
> + }
>
> dma->desc = dmaengine_prep_slave_sg(dma->chan, &dma->tx_sg, 1,
> DMA_MEM_TO_DEV,
> @@ -548,6 +551,7 @@ static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
> return 0;
> unmap:
> dma_unmap_sg(port->dev, &dma->tx_sg, 1, dma->dir);
> +zero_sg:
> sg_init_table(&dma->tx_sg, 1);
> return ret;
> }
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
