linux-kernel - RE: [PATCH] atmel_serial: Fix hang in set

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Date:	Mon, 8 Jun 2009 10:24:51 +0200
From:	"Eirik Aanonsen" <eaa@...medical.com>
To:	"Haavard Skinnemoen" <haavard.skinnemoen@...el.com>
Cc:	<kernel@...32linux.org>, <linux-kernel@...r.kernel.org>,
	"Nicolas Ferre" <Nicolas.FERRE@...el.com>,
	"Andrew Victor" <avictor.za@...il.com>,
	"Alan Cox" <alan@...rguk.ukuu.org.uk>
Subject: RE: [PATCH] atmel_serial: Fix hang in set_termios when crtscts is enabled

> 
> Fix it by removing the busy-loop altogether.
> 
> Reported-by: Eirik Aanonsen <eaa@...medical.com>
> Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@...el.com>
> ---
> I have not tested this patch yet. Eirik, can you give it a try?
> 
>  drivers/serial/atmel_serial.c |    8 +++++---
>  1 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/serial/atmel_serial.c
> b/drivers/serial/atmel_serial.c
> index b3497d7..338b15c 100644
> --- a/drivers/serial/atmel_serial.c
> +++ b/drivers/serial/atmel_serial.c
> @@ -1104,11 +1104,13 @@ static void atmel_set_termios(struct uart_port
> *port, struct ktermios *termios,
>  	/* update the per-port timeout */
>  	uart_update_timeout(port, termios->c_cflag, baud);
> 
> -	/* save/disable interrupts and drain transmitter */
> +	/*
> +	 * save/disable interrupts. The tty layer will ensure that the
> +	 * transmitter is empty if requested by the caller, so there's
> +	 * no need to wait for it here.
> +	 */
>  	imr = UART_GET_IMR(port);
>  	UART_PUT_IDR(port, -1);
> -	while (!(UART_GET_CSR(port) & ATMEL_US_TXEMPTY))
> -		cpu_relax();
> 
>  	/* disable receiver and transmitter */
>  	UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS);
> --
> 1.6.0.4

Works like a charm :) Thanx. I sis not use the patch but I just 
Added a 0& inside the condition to the while loop.


Regards
____________________________________________________
 
Eirik Aanonsen
SW Developer
E-mail: eaa@...medical.com 
Phone: +47 90 68 11 92
Fax: +47 37 03 56 77
____________________________________________________



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