linux-kernel - Re: [PATCH 2/2] stmmac: intel: Honor phy LED set by system firmware on a Dell hardware

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Date:   Fri, 14 Jan 2022 23:25:17 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     peppe.cavallaro@...com, alexandre.torgue@...s.st.com,
        joabreu@...opsys.com, "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Marek Behún <kabel@...nel.org>,
        Ivan Bornyakov <i.bornyakov@...rotek.ru>,
        Pali Rohár <pali@...nel.org>,
        netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] stmmac: intel: Honor phy LED set by system firmware
 on a Dell hardware

On Fri, Jan 14, 2022 at 9:20 PM Andrew Lunn <andrew@...n.ch> wrote:
>
> >  static void marvell_config_led(struct phy_device *phydev)
> >  {
> > -     u16 def_config;
> > +     struct marvell_priv *priv = phydev->priv;
> >       int err;
> >
> > -     switch (MARVELL_PHY_FAMILY_ID(phydev->phy_id)) {
> > -     /* Default PHY LED config: LED[0] .. Link, LED[1] .. Activity */
> > -     case MARVELL_PHY_FAMILY_ID(MARVELL_PHY_ID_88E1121R):
> > -     case MARVELL_PHY_FAMILY_ID(MARVELL_PHY_ID_88E1318S):
> > -             def_config = MII_88E1121_PHY_LED_DEF;
> > -             break;
> > -     /* Default PHY LED config:
> > -      * LED[0] .. 1000Mbps Link
> > -      * LED[1] .. 100Mbps Link
> > -      * LED[2] .. Blink, Activity
> > -      */
> > -     case MARVELL_PHY_FAMILY_ID(MARVELL_PHY_ID_88E1510):
> > -             if (phydev->dev_flags & MARVELL_PHY_LED0_LINK_LED1_ACTIVE)
> > -                     def_config = MII_88E1510_PHY_LED0_LINK_LED1_ACTIVE;
> > -             else
> > -                     def_config = MII_88E1510_PHY_LED_DEF;
> > -             break;
> > -     default:
> > +     if (priv->led_def_config == -1)
> >               return;
> > +
> > +     if (priv->led_def_config)
> > +             goto write;
>
> Really?
>
> Please restructure this code. Take it apart into helpers. You need:
>
> A function to set the actual LED configuration.
> A function to decide what, if any, configuration to set
> A function to store the current configuration on suspend.
> A function to restore the current configuration on resume.
>
> Lots of little functions will make it much easier to understand, and
> avoid 1980s BASIC style.

Sure, will turn these into helper functions.

>
> I'm also surprised you need to deal with suspend/resume. Why does the
> BIOS not set the LED mode on resume, same as it does on power up?

I was told this is a BIOS limitation. I'll ask vendor _why_ the LED
can't be restored by BIOS.

Kai-Heng

>
>       Andrew