Re: [PATCH v1 2/2] spi: Check if transfer is mapped before calling DMA sync APIs

[Nícolas F. R. A. Prado]

On Wed, May 22, 2024 at 02:41:51PM -0400, Nícolas F. R. A. Prado wrote:
> On Wed, May 22, 2024 at 08:09:50PM +0300, Andy Shevchenko wrote:
[..]
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index f94420858c22..9bc9fd10d538 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -1220,6 +1220,11 @@ void spi_unmap_buf(struct spi_controller *ctlr, struct device *dev,
>         spi_unmap_buf_attrs(ctlr, dev, sgt, dir, 0);
>  }
> 
> +/* Dummy SG for unidirect transfers */
> +static struct scatterlist dummy_sg = {
> +       .page_link = SG_END,
> +};
> +
>  static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
>  {
>         struct device *tx_dev, *rx_dev;
> @@ -1258,6 +1263,8 @@ static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
>                                                 attrs);
>                         if (ret != 0)
>                                 return ret;
> +               } else {
> +                       xfer->tx_sg.sgl = &dummy_sg;
>                 }
> 
>                 if (xfer->rx_buf != NULL) {
> @@ -1271,6 +1278,8 @@ static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
> 
>                                 return ret;
>                         }
> +               } else {
> +                       xfer->rx_sg.sgl = &dummy_sg;
>                 }
>         }
>         /* No transfer has been mapped, bail out with success */

Hi Andy,

I can send this patch to the list myself with your authorship, I just need your
SoB.

Thanks,
Nícolas