netdev - Re: [PATCH net-next 2/3] sh_eth: Convert to DEFINE_SIMPLE_DEV_PM

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Message-ID: <CAMuHMdU=Q6AZcryj1ZBGW+5F+iYvZCL=Eg0yPw0B4jnczmA8nw@mail.gmail.com>
Date: Mon, 8 Sep 2025 16:36:29 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Niklas Söderlund <niklas.soderlund@...natech.se>
Cc: Andrew Lunn <andrew@...n.ch>, Andrew Lunn <andrew+netdev@...n.ch>, 
	"David S . Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org, 
	linux-renesas-soc@...r.kernel.org, linux-sh@...r.kernel.org
Subject: Re: [PATCH net-next 2/3] sh_eth: Convert to DEFINE_SIMPLE_DEV_PM_OPS()

Hi Niklas,

On Fri, 5 Sept 2025 at 20:41, Niklas Söderlund
<niklas.soderlund@...natech.se> wrote:
> On 2025-09-05 13:57:05 +0200, Andrew Lunn wrote:
> > > You cannot enter system sleep without CONFIG_PM_SLEEP, so enabling
> > > WoL would be pointless.
> >
> > Yet get_wol will return WoL can be used, and set_wol will allow you to
> > configure it. It seems like EOPNOTSUPP would be better.
>
> Out of curiosity. Are you suggesting a compile time check/construct for
> CONFIG_PM_SLEEP be added in the driver itself, or in ethtool_set_wol()
> and ethtool_get_wol() in net/ethtool/ioctl.c to complement the
>
>     if (!dev->ethtool_ops->get_wol || !dev->ethtool_ops->set_wol)
>         return -EOPNOTSUPP;
>
> checks already there? To always return EOPNOTSUPP if PM_SLEEP is not
> selected?

Iff we want to go that route, I'd vote for handling it in common code.
Still, there is no guarantee that WoL will actually work, as on
some systems it may depend on the firmware, too.  E.g. on ARM
systems with PSCI, the SoC may be powered down during s2ram, so
there is no guarantee that any of the wake-up sources shown in
/sys/kernel/debug/wakeup_sources can actually wake up the system.
I tried having a mechanism to describe that in DT, but it was rejected.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds