Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753004AbbBAQ1j (ORCPT ); Sun, 1 Feb 2015 11:27:39 -0500 Received: from mail-qc0-f173.google.com ([209.85.216.173]:39848 "EHLO mail-qc0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753017AbbBAQ1e (ORCPT ); Sun, 1 Feb 2015 11:27:34 -0500 Message-ID: <54CE53F3.5040709@hurleysoftware.com> Date: Sun, 01 Feb 2015 11:27:31 -0500 From: Peter Hurley User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Eddie Huang , Rob Herring , Mark Rutland , Greg Kroah-Hartman , Matthias Brugger CC: devicetree@vger.kernel.org, Vladimir Murzin , srv_heupstream@mediatek.com, Pawel Moll , Ian Campbell , Catalin Marinas , Jonathan Corbet , Will Deacon , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, yh.chen@mediatek.com, Howard Chen , Ashwin Chaugule , linux-serial@vger.kernel.org, Kumar Gala , "Joe.C" , Jiri Slaby , linux-arm-kernel@lists.infradead.org, Alan Cox Subject: Re: [PATCH v2 1/4] tty: serial: Add 8250 earlycon to support noinit option References: <1421068104-30463-1-git-send-email-eddie.huang@mediatek.com> <1421068104-30463-2-git-send-email-eddie.huang@mediatek.com> In-Reply-To: <1421068104-30463-2-git-send-email-eddie.huang@mediatek.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4722 Lines: 125 Hi Eddie, On 01/12/2015 08:08 AM, Eddie Huang wrote: > Add earlycon support not only baudrate option, but also add noinit option. > If use noinit option, 8250 earlycon will not init serial hardware and use > loader setting. I see this went into Greg's tty-testing branch. The only point of this is to not program the divisor, right? I ask because early_serial8250_setup() could already handle this without extra options by simply not doing divisor programming if no baud option is present. And this blows up if the optional console= form is used: console=uart,mmio32,,noinit because the ttyS console will expect line settings for console match. Regards, Peter Hurley > Signed-off-by: Eddie Huang > --- > drivers/tty/serial/8250/8250_early.c | 7 ++++--- > drivers/tty/serial/earlycon.c | 17 ++++++++++++----- > include/linux/serial_8250.h | 2 ++ > include/linux/serial_core.h | 1 + > 4 files changed, 19 insertions(+), 8 deletions(-) > > diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c > index 4858b8a..a13d757 100644 > --- a/drivers/tty/serial/8250/8250_early.c > +++ b/drivers/tty/serial/8250/8250_early.c > @@ -138,19 +138,20 @@ static void __init init_port(struct earlycon_device *device) > serial8250_early_out(port, UART_LCR, c & ~UART_LCR_DLAB); > } > > -static int __init early_serial8250_setup(struct earlycon_device *device, > +int __init early_serial8250_setup(struct earlycon_device *device, > const char *options) > { > if (!(device->port.membase || device->port.iobase)) > return 0; > > - if (!device->baud) { > + if (!device->baud && !device->noinit) { > device->baud = probe_baud(&device->port); > snprintf(device->options, sizeof(device->options), "%u", > device->baud); > } > > - init_port(device); > + if (!device->noinit) > + init_port(device); > > early_device = device; > device->con->write = early_serial8250_write; > diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c > index 64fe25a..4891251 100644 > --- a/drivers/tty/serial/earlycon.c > +++ b/drivers/tty/serial/earlycon.c > @@ -58,7 +58,7 @@ static int __init parse_options(struct earlycon_device *device, > char *options) > { > struct uart_port *port = &device->port; > - int mmio, mmio32, length; > + int noinit, mmio, mmio32, length; > unsigned long addr; > > if (!options) > @@ -92,10 +92,17 @@ static int __init parse_options(struct earlycon_device *device, > options = strchr(options, ','); > if (options) { > options++; > - device->baud = simple_strtoul(options, NULL, 0); > - length = min(strcspn(options, " ") + 1, > - (size_t)(sizeof(device->options))); > - strlcpy(device->options, options, length); > + noinit = !strncmp(options, "noinit", 6); > + if (noinit) { > + device->noinit = noinit; > + strlcpy(device->options, options, 6); > + device->options[6] = '\0'; > + } else { > + device->baud = simple_strtoul(options, NULL, 0); > + length = min(strcspn(options, " ") + 1, > + (size_t)(sizeof(device->options))); > + strlcpy(device->options, options, length); > + } > } > > if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM32) > diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h > index e02acf0..0e26eec 100644 > --- a/include/linux/serial_8250.h > +++ b/include/linux/serial_8250.h > @@ -119,6 +119,8 @@ extern int serial8250_find_port(struct uart_port *p); > extern int serial8250_find_port_for_earlycon(void); > extern unsigned int serial8250_early_in(struct uart_port *port, int offset); > extern void serial8250_early_out(struct uart_port *port, int offset, int value); > +extern int early_serial8250_setup(struct earlycon_device *device, > + const char *options); > extern int setup_early_serial8250_console(char *cmdline); > extern void serial8250_do_set_termios(struct uart_port *port, > struct ktermios *termios, struct ktermios *old); > diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h > index 057038c..72c6698 100644 > --- a/include/linux/serial_core.h > +++ b/include/linux/serial_core.h > @@ -326,6 +326,7 @@ struct earlycon_device { > struct uart_port port; > char options[16]; /* e.g., 115200n8 */ > unsigned int baud; > + int noinit; > }; > int setup_earlycon(char *buf, const char *match, > int (*setup)(struct earlycon_device *, const char *)); > -- 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/