In order to display console messages in low power mode, console pins must be kept active after suspend call.
--- Initial patch "serial: stm32: add support for no_console_suspend" was part of "STM32 usart power improvement" series, but as dependancy to console_suspend pinctl state has been removed to fit with Rob comment [1], this patch has no more dependancy with any other patch of this series. [1] https://lkml.org/lkml/2019/7/9/451 Signed-off-by: Erwan Le Ray <erwan.le...@st.com> diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 9cfcf355567a..5afd29162f6c 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -1425,7 +1425,18 @@ static int __maybe_unused stm32_serial_suspend(struct device *dev) else stm32_serial_enable_wakeup(port, false); - pinctrl_pm_select_sleep_state(dev); + /* + * When "no_console_suspend" is enabled, keep the pinctrl default state + * and rely on bootloader stage to restore this state upon resume. + * Otherwise, apply the idle or sleep states depending on wakeup + * capabilities. + */ + if (console_suspend_enabled || !uart_console(port)) { + if (device_may_wakeup(dev)) + pinctrl_pm_select_idle_state(dev); + else + pinctrl_pm_select_sleep_state(dev); + } return 0; } -- 2.17.1
