serial: stm32: fix wake-up flag handling

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This patch fixes several issue with wake-up handling:
- the WUF irq is handled several times at wake-up
- the USART is disabled / enabled at suspend to set wake-up flag.
It can cause glitches during RX.

This patch fix those issues:
- clear wake-up flag and disable wake-up irq in WUF irq handling
- enable wake-up from low power on start bit detection at port
configuration
- Unmask the wake-up flag irq at suspend and mask it at resume

In addition, pm_wakeup_event handling is moved from receice_chars to WUF
irq handling.

Fixes: 270e5a74fe ("serial: stm32: add wakeup mechanism")
Signed-off-by: Erwan Le Ray <erwan.leray@foss.st.com>
Link: https://lore.kernel.org/r/20210304162308.8984-7-erwan.leray@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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This commit is contained in:

Erwan Le Ray 2021-03-04 17:23:01 +01:00 • committed by Greg Kroah-Hartman

parent ad76768124

commit 12761869f0

1 changed files with 19 additions and 13 deletions

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32

drivers/tty/serial/stm32-usart.c

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