From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: Re: [PATCH v2 1/4] tty: serial: Add 8250 earlycon to support noinit option Date: Sun, 01 Feb 2015 11:27:31 -0500 Message-ID: <54CE53F3.5040709@hurleysoftware.com> References: <1421068104-30463-1-git-send-email-eddie.huang@mediatek.com> <1421068104-30463-2-git-send-email-eddie.huang@mediatek.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1421068104-30463-2-git-send-email-eddie.huang-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Eddie Huang , Rob Herring , Mark Rutland , Greg Kroah-Hartman , Matthias Brugger Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Vladimir Murzin , srv_heupstream-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org, Pawel Moll , Ian Campbell , Catalin Marinas , Jonathan Corbet , Will Deacon , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, yh.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org, Howard Chen , Ashwin Chaugule , linux-serial-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Kumar Gala , "Joe.C" , Jiri Slaby , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Alan Cox List-Id: devicetree@vger.kernel.org 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 devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html