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serial-core: restore termios settings when resume console ports
The commit4547be7
rewrites suspend and resume functions. According to this rewrite, when a serial port is a printk console device and can suspend(without set no_console_suspend flag), it will definitely call set_termios function during its resume, but parameter termios isn't initialized, this will pass an unpredictable config to the serial port. If this serial port is not a userspace opened tty device , a suspend and resume action will make this serial port unusable. I.E. ttyS0 is a printk console device, ttyS1 or keyboard+display is userspace tty device, a suspend/resume action will make ttyS0 unusable. If a serial port is both a printk console device and an opened tty device, this issue can be overcome because it will call set_termios again with the correct parameter in the uart_change_speed function. Refer to the deleted content of commit4547be7
, revert parts relate to restore settings into parameter termios. It is safe because if a serial port is a printk console only device, the only meaningful field in termios is c_cflag and its old config is saved in uport->cons->cflag, if this port is also an opened tty device, it will clear uport->cons->cflag in the uart_open and the old config is saved in tty->termios. Signed-off-by: Jason Wang <jason77.wang@gmail.com> Acked-by: Stanislav Brabec <sbrabec@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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1 changed files with 12 additions and 0 deletions
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@ -2066,6 +2066,18 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
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* Re-enable the console device after suspending.
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*/
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if (console_suspend_enabled && uart_console(uport)) {
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/*
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* First try to use the console cflag setting.
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*/
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memset(&termios, 0, sizeof(struct ktermios));
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termios.c_cflag = uport->cons->cflag;
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/*
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* If that's unset, use the tty termios setting.
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*/
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if (port->tty && port->tty->termios && termios.c_cflag == 0)
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termios = *(port->tty->termios);
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uart_change_pm(state, 0);
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uport->ops->set_termios(uport, &termios, NULL);
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console_start(uport->cons);
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