linux-kernel - Re: [PATCH net v4] net: phy: meson-gxl: implement meson_gxl_phy

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Message-ID: <CACqvRUYUkeU9C_W47yPLSRb=+VL4Hti1+E2YQNLKQtcXw_H-OQ@mail.gmail.com>
Date:   Fri, 11 Aug 2023 04:45:26 -0400
From:   Da Xue <da@...re.computer>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Luke Lu <luke.lu@...re.computer>, Andrew Lunn <andrew@...n.ch>,
        Russell King <linux@...linux.org.uk>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Da Xue <da@...re.computer>
Subject: Re: [PATCH net v4] net: phy: meson-gxl: implement meson_gxl_phy_resume()

On Fri, Aug 11, 2023 at 2:07 AM Heiner Kallweit <hkallweit1@...il.com> wrote:
>
> On 09.08.2023 23:49, Luke Lu wrote:
> > From: Da Xue <da@...re.computer>
> >
> > While testing the suspend/resume function, we found the ethernet
> > is broken if using internal PHY of Amlogic meson GXL SoC.
> > After system resume back, the ethernet is down, no carrier found.
> >
> >       eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state
> >               DOWN group default qlen 1000
> >
> > In this patch, we re-initialize the internal PHY to fix this problem.
> >
>
> It's not an unusual case that system cuts power to the PHY during
> system suspend. So the PHY needs to be re-initialized on resume.
> That's why we call phy_init_hw() in mdio_bus_phy_resume().

Thanks for the review, Heiner.

We will rework this in v5.

>
> If going your way we would be better off calling .config_init()
> in genphy_resume(). Please check the MAC driver, maybe it's better
> to re-initialize the PHY in the resume path of the MAC driver.
>
> >       eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP
> >               group default qlen 1000
> >
> > Fixes: 7334b3e47aee ("net: phy: Add Meson GXL Internal PHY driver")
> > Signed-off-by: Da Xue <da@...re.computer>
> > Signed-off-by: Luke Lu <luke.lu@...re.computer>
> >
> > ---
> > Note, we don't Cc stable kernel tree in this patch intentionally, since
> > there will be a cherry-pick failure if apply this patch from kernel version
> > less than v6.2, it's not a logic failure but due to the changes too close.
> >
> > Please check commit 69ff53e4a4c9 ("net: phy: meson-gxl: use MMD access dummy stubs for GXL, internal PHY")
> > We plan to slightly rework the patch, and send it to stable tree separately
> > once this patch is accepted into mainline.
> >
> > v4:
> >  - refactor commit message to better explain the problem & fix
> >  - check return value of genphy_resume()
> >  - add 'net' annotation
> >  - add Fixes tag
> >
> > v3: https://lore.kernel.org/netdev/20230808050016.1911447-1-da@libre.computer
> >  - fix missing parameter of genphy_resume()
> >
> > v2: https://lore.kernel.org/netdev/20230804201903.1303713-1-da@libre.computer
> >  - call generic genphy_resume()
> >
> > v1: https://lore.kernel.org/all/CACqvRUZRyXTVQyy9bUviQZ+_moLQBjPc6nin_NQC+CJ37yNnLw@mail.gmail.com
> > ---
> >  drivers/net/phy/meson-gxl.c | 17 ++++++++++++++++-
> >  1 file changed, 16 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/phy/meson-gxl.c b/drivers/net/phy/meson-gxl.c
> > index bb9b33b6bce2..9ebe09b0cd8c 100644
> > --- a/drivers/net/phy/meson-gxl.c
> > +++ b/drivers/net/phy/meson-gxl.c
> > @@ -132,6 +132,21 @@ static int meson_gxl_config_init(struct phy_device *phydev)
> >       return 0;
> >  }
> >
> > +static int meson_gxl_phy_resume(struct phy_device *phydev)
> > +{
> > +     int ret;
> > +
> > +     ret = genphy_resume(phydev);
> > +     if (ret)
> > +             return ret;
> > +
> > +     ret = meson_gxl_config_init(phydev);
> > +     if (ret)
> > +             return ret;
> > +
> > +     return 0;
> > +}
> > +
> >  /* This function is provided to cope with the possible failures of this phy
> >   * during aneg process. When aneg fails, the PHY reports that aneg is done
> >   * but the value found in MII_LPA is wrong:
> > @@ -196,7 +211,7 @@ static struct phy_driver meson_gxl_phy[] = {
> >               .config_intr    = smsc_phy_config_intr,
> >               .handle_interrupt = smsc_phy_handle_interrupt,
> >               .suspend        = genphy_suspend,
> > -             .resume         = genphy_resume,
> > +             .resume         = meson_gxl_phy_resume,
> >               .read_mmd       = genphy_read_mmd_unsupported,
> >               .write_mmd      = genphy_write_mmd_unsupported,
> >       }, {
>