linux-kernel - Re: [PATCH v2 3/6] serial: imx: remove CTSC and CTS handling

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Date:   Wed, 5 Jul 2017 15:38:45 +0200
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Romain Perier <romain.perier@...labora.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-serial@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Nandor Han <nandor.han@...com>,
        Clemens Gruber <clemens.gruber@...ruber.com>,
        Fabio Estevam <fabio.estevam@....com>
Subject: Re: [PATCH v2 3/6] serial: imx: remove CTSC and CTS handling

Cc += Clemens Gruber + Fabio Estevam

On Wed, Jul 05, 2017 at 03:07:03PM +0200, Romain Perier wrote:
> From: Nandor Han <nandor.han@...com>
> 
> CTSC and CTS are not related to DMA and might add
> disruption in some cases.
> 
> Signed-off-by: Romain Perier <romain.perier@...labora.com>

If it was Nandor Han who created this patch, it would be great to get
his sob. If it was you, drop the From: line above.

> ---
>  drivers/tty/serial/imx.c | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 5291b86..dd3ebb4 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -1249,11 +1249,6 @@ static void imx_disable_dma(struct imx_port *sport)
>  	imx_stop_rx_dma(sport);
>  	imx_stop_tx_dma(sport);
>  
> -	/* clear UCR2 */
> -	temp = readl(sport->port.membase + UCR2);
> -	temp &= ~(UCR2_CTSC | UCR2_CTS | UCR2_ATEN);
> -	writel(temp, sport->port.membase + UCR2);
> -

Before this patch imx_disable_dma resulted in the #CTS pin being high
(inactive).

Does this qualify as a fix? If so, you should sort this patch to the
beginning of the series. Did you do test this patch and its effects
separately?

@Clemens: maybe this patch makes a relevant difference when the port is
operated in rs485 mode. Do you care to test?

>  	imx_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);
>  
>  	sport->dma_is_enabled = 0;
> -- 
> 1.8.3.1

Best regards
Uwe

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