Re: [PATCH] serial: 8250_omap: Set the console genpd always on if no console suspend

[Kevin Hilman <khilman@kernel.org>]

Tony Lindgren <tony@atomide.com> writes:

> * Kevin Hilman <khilman@kernel.org> [231128 04:05]:
>> Tony Lindgren <tony@atomide.com> writes:
>> 
>> > * Théo Lebrun <theo.lebrun@bootlin.com> [231124 10:39]:
>> >> On Fri Nov 24, 2023 at 6:37 AM CET, Tony Lindgren wrote:
>> >> Checking the code confirms this behavior. Grep for the macro
>> >> genpd_is_active_wakeup rather than GENPD_FLAG_ACTIVE_WAKEUP. It gets
>> >> used twice (suspend & resume), both in the same manner:
>> >> 
>> >>    if (device_wakeup_path(dev) && genpd_is_active_wakeup(genpd))
>> >> 
>> >> This means this flag won't have any impact on runtime PM handling of
>> >> power-domains. By the way, other users of the flag enable it at PD
>> >> registration & don't touch it afterwards.
>> >
>> > Setting GENPD_FLAG_ACTIVE_WAKEUP will block deeper idle states for
>> > the SoC most likely.
>> 
>> It doesn't affect idle states.  It only affects suspend states.
>> 
>> As Théo pointed out, system-wide suspend will ignores runtime PM
>> refcounts, so IMO, using this flag is the right approach.
>
> But it still blocks the deeper SoC suspend states if set, right?
>
> If so, it should be dynamically toggled depending on the console_suspend
> flag.

Agreed, and that's what I think Théo proposed earlier in this thread[1].

Since the deeper suspend states are prevented only when this flag is
present *and* the wakeup path is set, Théo's example just toggles the
wakeup path set based on console_suspend_enabled.

Kevin

[1] https://lore.kernel.org/r/CX5F88JLWFUW.Z36KQB2PX554@tleb-bootlin-xps13-01