Re: [PATCH v3 1/1] tty: serial: imx: allow breaks to be received when using dma

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

On Tue, Feb 20, 2018 at 10:20:37AM -0800, Troy Kisky wrote:
> This allows me to login after sending a break when service
> serial-getty@ttymxc0.service is running
> 
> The "tty_insert_flip_char(port, 0, TTY_BREAK)" in clear_rx_errors
> fixes this by allowing the higher layers to see a break.
> 
> Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
> Tested-by: Martin Hicks <mort@bork.org>
> 
> ---
> v2: rebase only
> v3: change commit message as requested by Fabio,
>     add tested-by
> ---
>  drivers/tty/serial/imx.c | 20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 1d7ca382bc12..2eb8c4a20d68 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -927,7 +927,6 @@ static void dma_rx_callback(void *data)
>  	status = dmaengine_tx_status(chan, (dma_cookie_t)0, &state);
>  
>  	if (status == DMA_ERROR) {
> -		dev_err(sport->port.dev, "DMA transaction error.\n");
>  		clear_rx_errors(sport);
>  		return;
>  	}
> @@ -1028,6 +1027,7 @@ static int start_rx_dma(struct imx_port *sport)
>  
>  static void clear_rx_errors(struct imx_port *sport)
>  {
> +	struct tty_port *port = &sport->port.state->port;
>  	unsigned int status_usr1, status_usr2;
>  
>  	status_usr1 = readl(sport->port.membase + USR1);
> @@ -1036,12 +1036,18 @@ static void clear_rx_errors(struct imx_port *sport)
>  	if (status_usr2 & USR2_BRCD) {
>  		sport->port.icount.brk++;
>  		writel(USR2_BRCD, sport->port.membase + USR2);
> -	} else if (status_usr1 & USR1_FRAMERR) {
> -		sport->port.icount.frame++;
> -		writel(USR1_FRAMERR, sport->port.membase + USR1);
> -	} else if (status_usr1 & USR1_PARITYERR) {
> -		sport->port.icount.parity++;
> -		writel(USR1_PARITYERR, sport->port.membase + USR1);
> +		if (tty_insert_flip_char(port, 0, TTY_BREAK) == 0)
> +			sport->port.icount.buf_overrun++;
> +		tty_flip_buffer_push(port);

I think this needs to call uart_handle_break() as imx_rxint() does. Not sure
how to properly handle SYSRQ in the dma case though.

> +	} else {
> +		dev_err(sport->port.dev, "DMA transaction error.\n");
> +		if (status_usr1 & USR1_FRAMERR) {
> +			sport->port.icount.frame++;
> +			writel(USR1_FRAMERR, sport->port.membase + USR1);
> +		} else if (status_usr1 & USR1_PARITYERR) {
> +			sport->port.icount.parity++;
> +			writel(USR1_PARITYERR, sport->port.membase + USR1);
> +		}
>  	}
>  
>  	if (status_usr2 & USR2_ORE) {
> -- 
> 2.14.1
> 
> 

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |