Johan Hovold <johan@xxxxxxxxxx> 于2019年5月14日周二 下午3:35写道: > > On Thu, May 09, 2019 at 01:42:39PM +0800, Lanqing Liu wrote: > > When userspace opens a serial port for console, uart_port_startup() > > is called. This function assigns the uport->cons->cflag value to > > TTY->termios.c_cflag, then it is cleared to 0. When the user space > > closes this serial port, the TTY structure will be released, and at > > this time uport->cons->cflag has also been cleared. > > > > On the Spreadtrum platform, in some special scenarios, like charging mode, > > userspace needs to close the console, which means the uport->cons->cflag > > has also been cleared. But printing logs is still needed in the kernel. So > > when system enters suspend and resume, the console needs to be configure > > the baud rate and data length of the serial port according to its own cflag > > when resuming the console port. At this time, the cflag is 0, which will > > cause serial port to produce configuration errors that do not meet user > > expectations. > > This is actually yet another regression due to 761ed4a94582 ("tty: > serial_core: convert uart_close to use tty_port_close") which > incidentally removed the call to uart_shutdown() where the cflag was > being saved precisely to avoid the problem you're describing: > > ae84db9661ca ("serial: core: Preserve termios c_cflag for console resume") Yes, agree with you. > > Judging from a quick look it seems the xmit buf, which is released in > that function may now be leaking too. We haven't found this issue before, but we can try to reproduce it on our platform. > > > To fix this, assigning the TTY->termios.c_cflag value to uport->cons->cflag > > before the userspace closes this console serial port. It will ensure that > > the correct cflag value can be gotten when the console serial port was > > resumed. > > Not sure this is the right fix, but I don't have time to look at this > right now. OK. Thanks for your comments.