RE: Linux-2.4.20 modem control

[Ed Vance <EdV@macrolink.com>]

On Thu, Mar 20, 2003 at 2:14 PM, Richard B. Johnson wrote:
> 
> [SNIPPED...]
> 
> This patch works (no other promises).
> 
> --- linux-2.4.20/drivers/char/serial.c.orig	2003-03-20 
> 16:21:55.000000000 -0500
> +++ linux-2.4.20/drivers/char/serial.c	2003-03-20 
> 16:31:23.000000000 -0500
> @@ -1538,8 +1538,12 @@
>  	serial_out(info, UART_LCR, serial_inp(info, UART_LCR) & 
> ~UART_LCR_SBC);
> 
>  	if (!info->tty || (info->tty->termios->c_cflag & HUPCL))
> -		info->MCR &= ~(UART_MCR_DTR|UART_MCR_RTS);
> -	serial_outp(info, UART_MCR, info->MCR);
> +        {
> +           serial_outp(info, UART_MCR,info->MCR & 
> ~(UART_MCR_DTR|UART_MCR_RTS));
> +           set_current_state(TASK_INTERRUPTIBLE);
> +           schedule_timeout(HZ/2);              /* 
> Disconnect modem  */
> +        }
> +	serial_outp(info, UART_MCR, info->MCR);  /* Don't keep it off */
> 
>  	/* disable FIFO's */
>  	serial_outp(info, UART_FCR, (UART_FCR_ENABLE_FIFO |
> 
Hi Richard,

I'm not sure it's a Good Thing(tm) to call schedule_timeout() with 
the interrupts disabled. The shutdown function is framed by 
save_flags();cli and restore_flags(). Don't know exactly what the 
downside of that could be. 

Is the re-enable of DTR actually necessary to get agetty to work? 
DTR is supposed to stay off until the next open. 

Still, if it works for you, it works. 

Cheers,
Ed

---------------------------------------------------------------- 
Ed Vance              edv (at) macrolink (dot) com
Macrolink, Inc.       1500 N. Kellogg Dr  Anaheim, CA  92807
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