From 4547be7809a3b775ce750ec7f8b5748954741523 Mon Sep 17 00:00:00 2001 From: Stanislav Brabec Date: Wed, 2 Dec 2009 16:20:56 +0100 Subject: [PATCH] serial-core: resume serial hardware with no_console_suspend 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 Tested-by: Daniel Mack Signed-off-by: Greg Kroah-Hartman --- drivers/serial/serial_core.c | 88 ++++++++++++++---------------------- 1 file changed, 33 insertions(+), 55 deletions(-) diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c index 047530b285bb..fa4f170f2e86 100644 --- a/drivers/serial/serial_core.c +++ b/drivers/serial/serial_core.c @@ -2006,12 +2006,6 @@ 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); @@ -2019,20 +2013,23 @@ 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. @@ -2047,16 +2044,18 @@ 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); @@ -2073,29 +2072,6 @@ 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); @@ -2121,21 +2097,23 @@ 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); -- 2.20.1