Message-ID: <83a8fb89ac7a69d08c9ea1422dade301dcc87297.camel@redhat.com>
Subject: Re: [PATCH V3 1/2] net: phylink: add a function to resume phy alone
 to fix resume issue with WoL enabled
From:   Paolo Abeni <pabeni@redhat.com>
To:     Clark Wang <xiaoning.wang@nxp.com>, peppe.cavallaro@st.com,
        alexandre.torgue@foss.st.com, joabreu@synopsys.com,
        davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        mcoquelin.stm32@gmail.com, linux@armlinux.org.uk, andrew@lunn.ch,
        hkallweit1@gmail.com
Cc:     netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-imx@nxp.com
Date:   Thu, 23 Feb 2023 11:09:04 +0100
In-Reply-To: <20230202081559.3553637-1-xiaoning.wang@nxp.com>
References: <20230202081559.3553637-1-xiaoning.wang@nxp.com>
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On Thu, 2023-02-02 at 16:15 +0800, Clark Wang wrote:
> Issue we met:
> On some platforms, mac cannot work after resumed from the suspend with Wo=
L
> enabled.
>=20
> The cause of the issue:
> 1. phylink_resolve() is in a workqueue which will not be executed immedia=
tely.
>    This is the call sequence:
>        phylink_resolve()->phylink_link_up()->pl->mac_ops->mac_link_up()
>    For stmmac driver, mac_link_up() will set the correct speed/duplex...
>    values which are from link_state.
> 2. In stmmac_resume(), it will call stmmac_hw_setup() after called the
>    phylink_resume(), because mac need phy rx_clk to do the reset.
>    stmmac_core_init() is called in function stmmac_hw_setup(), which will
>    reset the mac and set the speed/duplex... to default value.
> Conclusion: Because phylink_resolve() cannot determine when it is called,=
 it
>             cannot be guaranteed to be called after stmmac_core_init().
> 	    Once stmmac_core_init() is called after phylink_resolve(),
> 	    the mac will be misconfigured and cannot be used.
>=20
> In order to avoid this problem, add a function called phylink_phy_resume(=
)
> to resume phy separately. This eliminates the need to call phylink_resume=
()
> before stmmac_hw_setup().
>=20
> Add another judgement before called phy_start() in phylink_start(). This =
way
> phy_start() will not be called multiple times when resumes. At the same t=
ime,
> it may not affect other drivers that do not use phylink_phy_resume().
>=20
> Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
> ---
> V2 change:
>  - add mac_resume_phy_separately flag to struct phylink to mark if the ma=
c
>    driver uses the phylink_phy_resume() first.
> V3 change:
>  - add brace to avoid ambiguous 'else'
>    Reported-by: kernel test robot <lkp@intel.com>
> ---
>  drivers/net/phy/phylink.c | 32 ++++++++++++++++++++++++++++++--
>  include/linux/phylink.h   |  1 +
>  2 files changed, 31 insertions(+), 2 deletions(-)
>=20
> diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
> index 319790221d7f..c2fe66f0b78f 100644
> --- a/drivers/net/phy/phylink.c
> +++ b/drivers/net/phy/phylink.c
> @@ -80,6 +80,8 @@ struct phylink {
>  	DECLARE_PHY_INTERFACE_MASK(sfp_interfaces);
>  	__ETHTOOL_DECLARE_LINK_MODE_MASK(sfp_support);
>  	u8 sfp_port;
> +
> +	bool mac_resume_phy_separately;
>  };
> =20
>  #define phylink_printk(level, pl, fmt, ...) \
> @@ -1509,6 +1511,7 @@ struct phylink *phylink_create(struct phylink_confi=
g *config,
>  		return ERR_PTR(-EINVAL);
>  	}
> =20
> +	pl->mac_resume_phy_separately =3D false;
>  	pl->using_mac_select_pcs =3D using_mac_select_pcs;
>  	pl->phy_state.interface =3D iface;
>  	pl->link_interface =3D iface;
> @@ -1943,8 +1946,12 @@ void phylink_start(struct phylink *pl)
>  	}
>  	if (poll)
>  		mod_timer(&pl->link_poll, jiffies + HZ);
> -	if (pl->phydev)
> -		phy_start(pl->phydev);
> +	if (pl->phydev) {
> +		if (!pl->mac_resume_phy_separately)
> +			phy_start(pl->phydev);
> +		else
> +			pl->mac_resume_phy_separately =3D false;
> +	}
>  	if (pl->sfp_bus)
>  		sfp_upstream_start(pl->sfp_bus);
>  }
> @@ -2024,6 +2031,27 @@ void phylink_suspend(struct phylink *pl, bool mac_=
wol)
>  }
>  EXPORT_SYMBOL_GPL(phylink_suspend);
> =20
> +/**
> + * phylink_phy_resume() - resume phy alone
> + * @pl: a pointer to a &struct phylink returned from phylink_create()
> + *
> + * In the MAC driver using phylink, if the MAC needs the clock of the ph=
y
> + * when it resumes, can call this function to resume the phy separately.
> + * Then proceed to MAC resume operations.
> + */
> +void phylink_phy_resume(struct phylink *pl)
> +{
> +	ASSERT_RTNL();
> +
> +	if (!test_bit(PHYLINK_DISABLE_MAC_WOL, &pl->phylink_disable_state)
> +	    && pl->phydev) {
> +		phy_start(pl->phydev);
> +		pl->mac_resume_phy_separately =3D true;
> +	}
> +

Minor nit: the empty line here is not needed.

Cheers,

Paolo