Re: [PATCH v3] serial: sh-sci: Stop dmaengine transfer in sci_stop_tx()

[Sergei Shtylyov <sergei.shtylyov@gmail.com>]

On 6/9/21 4:49 AM, Yoshihiro Shimoda wrote:
> Stop dmaengine transfer in sci_stop_tx(). Otherwise, the following
> message is possible output when system enters suspend and while
> transferring data, because clearing TIE bit in SCSCR is not able to
> stop any dmaengine transfer.
> 
>     sh-sci e6550000.serial: ttySC1: Unable to drain transmitter
> 
> Note that this patch uses dmaengine_terminate_async() so that
> we can apply this patch into longterm kernel v4.9.x or later.
> 
> Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.")
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> ---
>  Changes from v2:
>  - Don't use a macro.
>  - Revise the commit descrption.
>  https://lore.kernel.org/linux-renesas-soc/20210604095704.756190-1-yoshihiro.shimoda.uh@renesas.com/
> 
>  Changes from v1:
>  - Don't put #ifdef in the .c file.
>  - Update the commit description.
>  https://lore.kernel.org/linux-renesas-soc/20210602114108.510527-1-yoshihiro.shimoda.uh@renesas.com/
> 
>  drivers/tty/serial/sh-sci.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
> index 4baf1316ea72..2d5487bf6855 100644
> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c
> @@ -610,6 +610,14 @@ static void sci_stop_tx(struct uart_port *port)
>  	ctrl &= ~SCSCR_TIE;
>  
>  	serial_port_out(port, SCSCR, ctrl);
> +
> +#ifdef CONFIG_SERIAL_SH_SCI_DMA

   Why not use IS_ENABLED() instead? Gets rid of #ifdef. :-)

> +	if (to_sci_port(port)->chan_tx &&
> +	    !dma_submit_error(to_sci_port(port)->cookie_tx)) {
> +		dmaengine_terminate_async(to_sci_port(port)->chan_tx);
> +		to_sci_port(port)->cookie_tx = -EINVAL;
> +	}
> +#endif
>  }
>  
>  static void sci_start_rx(struct uart_port *port)

MBR, Sergei