Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758888AbXENTTd (ORCPT ); Mon, 14 May 2007 15:19:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754566AbXENTTX (ORCPT ); Mon, 14 May 2007 15:19:23 -0400 Received: from caramon.arm.linux.org.uk ([217.147.92.249]:3970 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754576AbXENTTW (ORCPT ); Mon, 14 May 2007 15:19:22 -0400 Date: Mon, 14 May 2007 20:19:05 +0100 From: Russell King To: Yinghai Lu Cc: Andrew Morton , Andi Kleen , bjorn.helgaas@hp.com, Randy Dunlap , Linux Kernel Mailing List Subject: Re: [PATCH] serial: set RTS and DTR if flow is 'r' --- resend Message-ID: <20070514191905.GE29682@flint.arm.linux.org.uk> Mail-Followup-To: Yinghai Lu , Andrew Morton , Andi Kleen , bjorn.helgaas@hp.com, Randy Dunlap , Linux Kernel Mailing List References: <86802c440705122233y327756e7te534199f46b2059d@mail.gmail.com> <46489BC2.6040403@sun.com> <4648A310.1050908@sun.com> <20070514181007.GA29682@flint.arm.linux.org.uk> <4648B2CC.2020403@sun.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4648B2CC.2020403@sun.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1968 Lines: 59 On Mon, May 14, 2007 at 12:04:44PM -0700, Yinghai Lu wrote: > Russell King wrote: > >There may be some sense, however, in allowing DTR to be permanently > >raised for serial consoles. However, I would err on caution since > >DTR is used to reliably instruct modems to drop the line, so making > >such a change would be undesirable for those folk. > > > please check following is OK. Still wrong, and unfortunately you haven't understood what I was saying at all because this is worse. ;( Do not put the code in serial8250_set_termios. It is the wrong place. > > YH > > [PATCH] serial: set DTR in uart for kernel serial console > > Some UARTs on other side need host uart DTR is set, otherwise will not > receive char from the host that kernel is runing during kernel boot stage. > > BTW: > earlyprintk and early_uart are hard coded to set DTR/RTS. > > Signed-off-by: Yinghai Lu > Cc: Russell King > Cc: Andi Kleen > Cc: Bjorn Helgaas > > *diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c* > index 48e259a..29c051c 100644 > *--- a/drivers/serial/8250.c* > *+++ b/drivers/serial/8250.c* > @@ -2154,6 +2154,12 @@ serial8250_set_termios(struct uart_port *port, > struct ktermios *termios, > } > serial_outp(up, UART_FCR, fcr); /* set fcr */ > } > + > + /* some uarts on other side don't support no flow control. So we set > + * DTR in host uart to make them happy > + */ > + up->port.mctrl |= TIOCM_DTR; > + > serial8250_set_mctrl(&up->port, up->port.mctrl); > spin_unlock_irqrestore(&up->port.lock, flags); > } > -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/