linux-kernel - Re: [PATCH] serial: Two branches the same in timbuart_set

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Message-ID: <4B9E0160.5000900@pelagicore.com>
Date:	Mon, 15 Mar 2010 10:44:00 +0100
From:	Richard Röjfors <richard.rojfors@...agicore.com>
To:	Roel Kluin <roel.kluin@...il.com>
Cc:	linux-serial@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH] serial: Two branches the same in timbuart_set_mctrl()

Hi Roel,

On 01/17/2010 08:02 PM, Roel Kluin wrote:
> Dear Richard Röjfors,
>
> It is possible that I found a bug in the Timberdale UART driver that was added
> to the linux kernel. The patch below tries to fix this, note the RTS to CTS
> change, could you confirm whether the patch below changes your driver
> correctly?

Thanks for finding this, I have a comment on the patch below.

>
> Thank you,
>
> Roel Kluin
> ----------------->8----------------------------8<-------------------------------
> Regardless of whether the TIOCM_RTS bit was set in mctrl, the same write
> occurred.
>
> Signed-off-by: Roel Kluin<roel.kluin@...il.com>
> ---
>   drivers/serial/timbuart.c |    2 +-
>   1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/serial/timbuart.c b/drivers/serial/timbuart.c
> index 34b31da..c433d40 100644
> --- a/drivers/serial/timbuart.c
> +++ b/drivers/serial/timbuart.c
> @@ -219,7 +219,7 @@ static void timbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
>   	if (mctrl&  TIOCM_RTS)
>   		iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
>   	else
> -		iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
> +		iowrite8(TIMBUART_CTRL_CTS, port->membase + TIMBUART_CTRL);

This is not completely correct. CTS is a read only bit and we are to stop signal RTS.
So the line should look like:
iowrite8(0, port->membase + TIMBUART_CTRL);


>   }
>
>   static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier)

--Richard
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