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authorJason Wang <jason77.wang@gmail.com>2010-08-21 15:14:42 +0800
committerGreg Kroah-Hartman <gregkh@suse.de>2010-10-22 10:20:02 -0700
commit891b9dd10764352926e1e107756aa229dfa2c210 (patch)
tree62b3ce0f32123fdd8de05044da2d06194ef90fdc
parentca2e71aa8cfb0056ce720f3fd53f59f5fac4a3e1 (diff)
serial-core: restore termios settings when resume console ports
The commit 4547be7 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 commit 4547be7, 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>
-rw-r--r--drivers/serial/serial_core.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index ff21200f94f..bc6cddd1029 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -2066,6 +2066,18 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
* Re-enable the console device after suspending.
*/
if (console_suspend_enabled && uart_console(uport)) {
+ /*
+ * 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 (port->tty && port->tty->termios && termios.c_cflag == 0)
+ termios = *(port->tty->termios);
+
uart_change_pm(state, 0);
uport->ops->set_termios(uport, &termios, NULL);
console_start(uport->cons);