Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754641AbZLBPTz (ORCPT ); Wed, 2 Dec 2009 10:19:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753640AbZLBPTy (ORCPT ); Wed, 2 Dec 2009 10:19:54 -0500 Received: from cantor.suse.de ([195.135.220.2]:37086 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753365AbZLBPTy (ORCPT ); Wed, 2 Dec 2009 10:19:54 -0500 Subject: [PATCH]serial-core: resume serial hardware with no_console_suspend (resend) From: Stanislav Brabec To: Andrew Morton Cc: linux@arm.linux.org.uk, linux-kernel@vger.kernel.org, alan@lxorguk.ukuu.org.uk, gregkh@suse.de, Pavel Machek , Daniel Mack , saxena@laptop.org, Eric Miao , s.hauer@pengutronix.de, Haojian Zhuang Content-Type: text/plain; charset="ISO-8859-2" Organization: SuSE CR, s. r. o. Date: Wed, 02 Dec 2009 16:20:56 +0100 Message-Id: <1259767256.8709.323.camel@hammer.suse.cz> Mime-Version: 1.0 X-Mailer: Evolution 2.28.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6220 Lines: 194 Perform a tricky suspend/resume even with no_console_suspend. With no_console_suspend, kernel skips serial port suspend/resume and the serial hardware may remain in undefined state after resume. It actually happens on devices that don't have BIOS that handle serial initialization. It makes impossible to use serial console after resume. Devices affected by this problem include: Sharp Zaurus devices Several PXA based ARM embedded boards The patch does: - Save the hardware state - Perform buffer flush in time of its suspend call - Tell the driver that port is suspended - But still accept new data - And keep console hardware in state that allows to send them It allows to capture late console messages without breaking console after resume. This is just a resend of a patch discussed in these threads, as the patch was not yet applied. "Possible suspend/resume regression in .32-rc?" (Nov 1-5, 2009, ARM list, later LKML) "serial-core: resume serial hardware with no_console_suspend" (Sep 15-Oct 18, 2009, LKML & ARM lists) Signed-off-by: Stanislav Brabec Tested-by: Haojian Zhuang diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c index dcc7244..f1e1ab2 100644 --- a/drivers/serial/serial_core.c +++ b/drivers/serial/serial_core.c @@ -2008,12 +2008,6 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport) mutex_lock(&port->mutex); - if (!console_suspend_enabled && uart_console(uport)) { - /* we're going to avoid suspending serial console */ - mutex_unlock(&port->mutex); - return 0; - } - tty_dev = device_find_child(uport->dev, &match, serial_match_port); if (device_may_wakeup(tty_dev)) { enable_irq_wake(uport->irq); @@ -2021,20 +2015,23 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport) mutex_unlock(&port->mutex); return 0; } - uport->suspended = 1; + if (console_suspend_enabled || !uart_console(uport)) + uport->suspended = 1; if (port->flags & ASYNC_INITIALIZED) { const struct uart_ops *ops = uport->ops; int tries; - set_bit(ASYNCB_SUSPENDED, &port->flags); - clear_bit(ASYNCB_INITIALIZED, &port->flags); + if (console_suspend_enabled || !uart_console(uport)) { + set_bit(ASYNCB_SUSPENDED, &port->flags); + clear_bit(ASYNCB_INITIALIZED, &port->flags); - spin_lock_irq(&uport->lock); - ops->stop_tx(uport); - ops->set_mctrl(uport, 0); - ops->stop_rx(uport); - spin_unlock_irq(&uport->lock); + spin_lock_irq(&uport->lock); + ops->stop_tx(uport); + ops->set_mctrl(uport, 0); + ops->stop_rx(uport); + spin_unlock_irq(&uport->lock); + } /* * Wait for the transmitter to empty. @@ -2049,16 +2046,18 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport) drv->dev_name, drv->tty_driver->name_base + uport->line); - ops->shutdown(uport); + if (console_suspend_enabled || !uart_console(uport)) + ops->shutdown(uport); } /* * Disable the console device before suspending. */ - if (uart_console(uport)) + if (console_suspend_enabled && uart_console(uport)) console_stop(uport->cons); - uart_change_pm(state, 3); + if (console_suspend_enabled || !uart_console(uport)) + uart_change_pm(state, 3); mutex_unlock(&port->mutex); @@ -2075,29 +2074,6 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport) mutex_lock(&port->mutex); - if (!console_suspend_enabled && uart_console(uport)) { - /* no need to resume serial console, it wasn't suspended */ - /* - * First try to use the console cflag setting. - */ - memset(&termios, 0, sizeof(struct ktermios)); - termios.c_cflag = uport->cons->cflag; - /* - * If that's unset, use the tty termios setting. - */ - if (termios.c_cflag == 0) - termios = *state->port.tty->termios; - else { - termios.c_ispeed = termios.c_ospeed = - tty_termios_input_baud_rate(&termios); - termios.c_ispeed = termios.c_ospeed = - tty_termios_baud_rate(&termios); - } - uport->ops->set_termios(uport, &termios, NULL); - mutex_unlock(&port->mutex); - return 0; - } - tty_dev = device_find_child(uport->dev, &match, serial_match_port); if (!uport->suspended && device_may_wakeup(tty_dev)) { disable_irq_wake(uport->irq); @@ -2123,21 +2099,23 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport) spin_lock_irq(&uport->lock); ops->set_mctrl(uport, 0); spin_unlock_irq(&uport->lock); - ret = ops->startup(uport); - if (ret == 0) { - uart_change_speed(state, NULL); - spin_lock_irq(&uport->lock); - ops->set_mctrl(uport, uport->mctrl); - ops->start_tx(uport); - spin_unlock_irq(&uport->lock); - set_bit(ASYNCB_INITIALIZED, &port->flags); - } else { - /* - * Failed to resume - maybe hardware went away? - * Clear the "initialized" flag so we won't try - * to call the low level drivers shutdown method. - */ - uart_shutdown(state); + if (console_suspend_enabled || !uart_console(uport)) { + ret = ops->startup(uport); + if (ret == 0) { + uart_change_speed(state, NULL); + spin_lock_irq(&uport->lock); + ops->set_mctrl(uport, uport->mctrl); + ops->start_tx(uport); + spin_unlock_irq(&uport->lock); + set_bit(ASYNCB_INITIALIZED, &port->flags); + } else { + /* + * Failed to resume - maybe hardware went away? + * Clear the "initialized" flag so we won't try + * to call the low level drivers shutdown method. + */ + uart_shutdown(state); + } } clear_bit(ASYNCB_SUSPENDED, &port->flags); -- Best Regards / S pozdravem, Stanislav Brabec software developer --------------------------------------------------------------------- SUSE LINUX, s. r. o. e-mail: sbrabec@suse.cz Lihovarsk? 1060/12 tel: +420 284 028 966, +49 911 740538747 190 00 Praha 9 fax: +420 284 028 951 Czech Republic http://www.suse.cz/ -- 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/