Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756684AbYJQPhX (ORCPT ); Fri, 17 Oct 2008 11:37:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754654AbYJQPhH (ORCPT ); Fri, 17 Oct 2008 11:37:07 -0400 Received: from willie.n0ano.com ([64.66.241.76]:50722 "EHLO xolotl.n0ano.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755343AbYJQPhG (ORCPT ); Fri, 17 Oct 2008 11:37:06 -0400 From: n0ano@n0ano.com Date: Fri, 17 Oct 2008 09:36:52 -0600 To: Bjorn Helgaas Cc: n0ano@n0ano.com, Alan Cox , donald.d.dugger@intel.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Enable console on PCI serial devices Message-ID: <20081017153652.GH14490@xolotl.n0ano.com> References: <200810142231.m9EMV95O002974@los-vmm.sc.intel.com> <20081017102858.1f1d77f7@lxorguk.ukuu.org.uk> <20081017141102.GG14490@xolotl.n0ano.com> <200810170846.41032.bjorn.helgaas@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200810170846.41032.bjorn.helgaas@hp.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2783 Lines: 65 On Fri, Oct 17, 2008 at 08:46:40AM -0600, Bjorn Helgaas wrote: >... > this text is a little confusing. Since you multiply by 16 below, the > number specified by the user isn't really the crystal frequency, is it? Can't argue with that. How about this patch which describes the parameter more acurately as a multiplier. Signed-off-by: Don Dugger diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 82c561f..6e5334d 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -505,12 +505,15 @@ and is between 256 and 4096 characters. It is defined in the file Documentation/networking/netconsole.txt for an alternative. - uart[8250],io,[,options] - uart[8250],mmio,[,options] + uart[8250],io,[,options[,mult]] + uart[8250],mmio,[,options[,mult]] Start an early, polled-mode console on the 8250/16550 UART at the specified I/O port or MMIO address, switching to the matching ttyS device later. The - options are the same as for ttyS, above. + "options" are the same as for ttyS, above. "mult" + is a multiplier defining the crystal frequency which + defaults to 115200 (typically the fastest baud rate + supported by the uart). If the device connected to the port is not a TTY but a braille device, prepend "brl," before the device type, for instance @@ -518,8 +521,8 @@ and is between 256 and 4096 characters. It is defined in the file For now, only VisioBraille is supported. earlycon= [KNL] Output early console device and options. - uart[8250],io,[,options] - uart[8250],mmio,[,options] + uart[8250],io,[,options,[mult]] + uart[8250],mmio,[,options,[mult]] Start an early, polled-mode console on the 8250/16550 UART at the specified I/O port or MMIO address. The options are the same as for ttyS, above. diff --git a/drivers/serial/8250_early.c b/drivers/serial/8250_early.c index f279745..edd5803 100644 --- a/drivers/serial/8250_early.c +++ b/drivers/serial/8250_early.c @@ -180,6 +180,11 @@ static int __init parse_options(struct early_serial8250_device *device, snprintf(device->options, sizeof(device->options), "%u", device->baud); } + options = strchr(options, ','); + if (options) { + options++; + port->uartclk = simple_strtoul(options, NULL, 0) * 16; + } printk(KERN_INFO "Early serial console at %s 0x%llx (options '%s')\n", mmio ? "MMIO" : "I/O port", -- 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/