netdev - Re: [PATCH v2] net: phy: marvell: Honor phy LED set by system firmware on a Dell hardware

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Date:   Fri, 21 Jan 2022 22:04:08 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     hkallweit1@...il.com, linux@...linux.org.uk,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] net: phy: marvell: Honor phy LED set by system
 firmware on a Dell hardware

On Fri, Jan 21, 2022 at 9:05 PM Andrew Lunn <andrew@...n.ch> wrote:
>
> > > Since you talked about suspend/resume, does this machine support WoL?
> > > Is the BIOS configuring LED2 to be used as an interrupt when WoL is
> > > enabled in the BIOS? Do you need to save/restore that configuration
> > > over suspend/review? And prevent the driver from changing the
> > > configuration?
> >
> > This NIC on the machine doesn't support WoL.
>
> I'm surprised about that. Are you really sure?

Yes I am sure.

>
> What are you doing for resume? pressing the power button?

Power button, RTC. The system has another igb NIC, which supports WoL.

>
> > > > +static const struct dmi_system_id platform_flags[] = {
> > > > +     {
> > > > +             .matches = {
> > > > +                     DMI_MATCH(DMI_SYS_VENDOR, "Dell EMC"),
> > > > +                     DMI_MATCH(DMI_PRODUCT_NAME, "Edge Gateway 3200"),
> > > > +             },
> > > > +             .driver_data = (void *)PHY_USE_FIRMWARE_LED,
> > > > +     },
> > >
> > > This needs a big fat warning, that it will affect all LEDs for PHYs
> > > which linux is driving, on that machine. So PHYs on USB dongles, PHYs
> > > in SFPs, PHYs on plugin PCIe card etc.
> > >
> > > Have you talked with Dells Product Manager and do they understand the
> > > implications of this?
> >
> > Right, that's why the original approach is passing the flag from the MAC driver.
> > That approach can be more specific and doesn't touch unrelated PHYs.
>
> More specific, but still will go wrong at some point, A PCEe card
> using that MAC etc. And this is general infrastructure you are adding
> here, it can be used by any machine, any combination of MAC and PHY
> etc. So you need to clearly document its limits so others are not
> surprised.

The dwmac-intel device is an integrated end point connects directly to
the host bridge, so it won't be in a form of PCIe addin card.

Kai-Heng

>
>         Andrew