serial: stm32: add no_console_suspend support
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.leray@st.com>
Link: https://lore.kernel.org/r/20200519094104.27082-1-erwan.leray@st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 7d1acb3..8602ff3 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -1424,7 +1424,18 @@ 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;
}