Subject: Re: [PATCH v2 1/2] net: stmmac: fix pinctrl management during suspend/resume

From: "Russell King (Oracle)" <[email-masked]>
Date: Mon, 16 Mar 2026 09:03:14 +0000

On Sat, Mar 14, 2026 at 12:37:19AM +0000, Russell King (Oracle) wrote:
> On Sat, Mar 14, 2026 at 12:44:56AM +0100, Linus Walleij wrote:
> > On Fri, Mar 13, 2026 at 12:08 PM Russell King (Oracle)
> > <[email-masked]> wrote:
> > > On Fri, Mar 13, 2026 at 11:57:16AM +0100, Christophe Roullier wrote:
> > > > In the deepest low-power modes, the pinctrl configuration is lost
> > > > and is never restored if the interface is down.
> > > > This commit ensures that the pinctrl state is set in all cases.
> > >
> > > Shouldn't the pin state be restored by the pinctrl layer?
> > 
> > What we have in the device core only applies "init" and "default"
> > states, and provides these handles for transitioning to "sleep"
> > and "default" again (like a state machine).
> 
> What I was meaning is that - for a driver using the "default" state,
> if the hardware loses the pinctrl state during sleep, isn't it the
> responsibility of the pinctrl driver to restore the state rather
> than leaving it in whatever states it happens to be when the SoC
> comes back from suspend?
> 
> If that is not the case, then don't we have a major issue where
> drivers using pinctrl but do not issue any pinctrl calls in the
> resume function are buggy?

I would like an answer on this before this patch is merged, because
even with your reviewed-by, I don't think this patch is correct.

For example, if pinctrl loses the pinmux state across suspend/resume,
then this patch only solves the case where the NIC is down when
suspending.

It does not address the case where the NIC is up but WoL is disabled.
Also, what happens when WoL is enabled at the MAC, when we expect the
NIC to still be functional - which means that the pinmux state must
remain active over suspend.

This is in addition to a more general concern that almost every driver
in the kernel is likely broken if we need to switch pinmux modes on
resume to ensure that the "default" pinmux state is restored upon
resume, which seems to be what you're saying by giving a r-b for this
patch.

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