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Date: Fri, 24 Nov 2023 12:54:55 +0200
From: Tony Lindgren <tony@atomide.com>
To: =?utf-8?B?VGjDqW8=?= Lebrun <theo.lebrun@bootlin.com>
Cc: Kevin Hilman <khilman@kernel.org>,
	Thomas Richard <thomas.richard@bootlin.com>,
	gregkh@linuxfoundation.org, jirislaby@kernel.org,
	linux-serial@vger.kernel.org, gregory.clement@bootlin.com,
	u-kumar1@ti.com, d-gole@ti.com, thomas.petazzoni@bootlin.com
Subject: Re: [PATCH] serial: 8250_omap: Set the console genpd always on if no
 console suspend
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* 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.

> There is currently nothing that links the runtime PM refcount to whether
> or not the power-domains get powered-off at suspend_noirq. Should that
> change? Maybe, but it would be a big behavioral change.

For managing GENPD_FLAG_ACTIVE_WAKEUP dynamically, maybe something like:

device_request_wakeup_path(dev)
...
device_free_wakeup_path(dev)

And those would toggle GENPD_FLAG_ACTIVE_WAKEUP for the power domain
based on some usage count?

Regards,

Tony