On Thu, May 10, 2018 at 09:00:48AM +0200, Marek Szyprowski wrote:
> DMA engine driver might not always provide all the features needed by
> serial driver to properly operate in DMA mode, so check that before
> selecting DMA mode.
>
> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> ---
> drivers/tty/serial/samsung.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
> index 64e96926f1ad..334b53c6eb14 100644
> --- a/drivers/tty/serial/samsung.c
> +++ b/drivers/tty/serial/samsung.c
> @@ -856,6 +856,7 @@ static void s3c24xx_serial_break_ctl(struct uart_port *port, int break_state)
> static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
> {
> struct s3c24xx_uart_dma *dma = p->dma;
> + struct dma_slave_caps dma_caps;
> int ret;
>
> /* Default slave configuration parameters */
> @@ -874,6 +875,13 @@ static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
> if (IS_ERR(dma->rx_chan))
> return PTR_ERR(dma->rx_chan);
>
> + ret = dma_get_slave_caps(dma->rx_chan, &dma_caps);
> + if (ret < 0 ||
> + dma_caps.residue_granularity < DMA_RESIDUE_GRANULARITY_BURST) {
Let's print here reason of DMA setup failure? Later only generic message
about not using DMA would be shown.
The same in second path.
Best regards,
Krzysztof
> + ret = -ENODEV;
> + goto err_release_rx;
> + }
> +
> dmaengine_slave_config(dma->rx_chan, &dma->rx_conf);
>
> dma->tx_chan = dma_request_chan(p->port.dev, "tx");
> @@ -882,6 +890,13 @@ static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
> goto err_release_rx;
> }
>
> + ret = dma_get_slave_caps(dma->tx_chan, &dma_caps);
> + if (ret < 0 ||
> + dma_caps.residue_granularity < DMA_RESIDUE_GRANULARITY_BURST) {
> + ret = -ENODEV;
> + goto err_release_tx;
> + }
> +
> dmaengine_slave_config(dma->tx_chan, &dma->tx_conf);
>
> /* RX buffer */
> --
> 2.17.0
>
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