drivers: serial: stm32: add reinit after standby
When resuming from low power mode, if UART is disabled, this means that
we come from a mode that reset the registers, so we redo a full init of
the driver.
Signed-off-by: Guillaume Gautier <guillaume.gautier-ext@st.com>
diff --git a/drivers/serial/uart_stm32.c b/drivers/serial/uart_stm32.c
index cba80aa..107dd88 100644
--- a/drivers/serial/uart_stm32.c
+++ b/drivers/serial/uart_stm32.c
@@ -2081,17 +2081,26 @@
switch (action) {
case PM_DEVICE_ACTION_RESUME:
- /* Set pins to active state */
- err = pinctrl_apply_state(config->pcfg, PINCTRL_STATE_DEFAULT);
- if (err < 0) {
- return err;
- }
+ /* When exiting low power mode, check whether UART is enabled.
+ * If not, it means we are exiting Suspend to RAM mode (STM32
+ * Standby), and the driver need to be reinitialized
+ */
+ if (LL_USART_IsEnabled(config->usart)) {
+ /* Set pins to active state */
+ err = pinctrl_apply_state(config->pcfg, PINCTRL_STATE_DEFAULT);
+ if (err < 0) {
+ return err;
+ }
- /* enable clock */
- err = clock_control_on(data->clock, (clock_control_subsys_t)&config->pclken[0]);
- if (err != 0) {
- LOG_ERR("Could not enable (LP)UART clock");
- return err;
+ /* enable clock */
+ err = clock_control_on(data->clock,
+ (clock_control_subsys_t)&config->pclken[0]);
+ if (err != 0) {
+ LOG_ERR("Could not enable (LP)UART clock");
+ return err;
+ }
+ } else {
+ uart_stm32_init(dev);
}
break;
case PM_DEVICE_ACTION_SUSPEND:
