Re: [PATCH 0/6] tty: serial: propagate errors from uart_ops.pm callback

[Tony Lindgren]

On Fri, Jul 10, 2026 at 07:37:46AM +0300, Tony Lindgren wrote:
> * Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> [260709 10:38]:
> > Note, that Tony (you have him in the Cc list) did a lot for some corner cases
> > with that and we still have them IIRC. Tony, do you know what is the state of
> > affairs with runtime PM for UART?
> 
> The RX side of things should work for hardware that can wake up to an incoming
> event. Linux for sure needs more work to properly handle the various corner case
> TX wake-up of a PM runtime idled UART. I'm mostly offline until Monday though,
> will check my notes for more details next week.

For the TX side handling, my understanding is that at least uart_update_mctrl()
needs to call PM runtime resume and put autosuspend. And we should assume
uart_update_mctrl() can sleep to resume the PM runtime suspended serial port.

For drivers, the callers of uport->ops->get/set_mctrl() should be updated
to use uart_update_mctrl() where possible. And the remaining ones that cannot
sleep should be fixed so they can sleep or have PM runtime disabled.

Anybody have better ideas?

Regards,

Tony