On Sun, Oct 09, 2022 at 10:23:13AM +0000, Sherry Sun wrote: > I am not familiar with 8250 serial, but at least for imx uart driver > and lpuart driver, the following behavior is same. > For the "real" consoles (everything which is not a bootconsole), > the (port)->cons and (port)->cons->index are initialized through > uart_add_one_port()->uart_configure_port()->register_console()-> > try_enable_new_console(), here the console index is assigned by > the console cmdline parameters. Hm, uart_add_one_port() does the following *before* calling uart_configure_port(): /* * If this port is in use as a console then the spinlock is already * initialised. */ if (!uart_console_enabled(uport)) uart_port_spin_lock_init(uport); It sounds like in the case of fsl_lpuart.c, the spin lock is *always* initialized, even though a concurrent lpuart_console_write() may be holding it. That's not solved by moving lpuart_global_reset() around. The problem with performing lpuart_global_reset() after UART registration is that as soon as uart_add_one_port() returns, the port is available for user space to use. So resetting it is a no-go. Thanks, Lukas
