netdev - Re: [PATCH net-next 3/3] net: ethernet: renesas: rswitch: Add phy_power

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Date:   Tue, 3 Jan 2023 09:56:00 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
Cc:     andrew@...n.ch, hkallweit1@...il.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        netdev@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH net-next 3/3] net: ethernet: renesas: rswitch: Add
 phy_power_{on,off}() calling

On Mon, Dec 26, 2022 at 04:14:25PM +0900, Yoshihiro Shimoda wrote:
> Some Ethernet PHYs (like marvell10g) will decide the host interface
> mode by the media-side speed. So, the rswitch driver needs to
> initialize one of the Ethernet SERDES (r8a779f0-eth-serdes) ports
> after linked the Ethernet PHY up. The r8a779f0-eth-serdes driver has
> .init() for initializing all ports and .power_on() for initializing
> each port. So, add phy_power_{on,off} calling for it.
> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
> ---
>  drivers/net/ethernet/renesas/rswitch.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
> index ca79ee168206..2f335c95f5a8 100644
> --- a/drivers/net/ethernet/renesas/rswitch.c
> +++ b/drivers/net/ethernet/renesas/rswitch.c
> @@ -1180,6 +1180,10 @@ static void rswitch_mac_link_down(struct phylink_config *config,
>  				  unsigned int mode,
>  				  phy_interface_t interface)
>  {
> +	struct net_device *ndev = to_net_dev(config->dev);
> +	struct rswitch_device *rdev = netdev_priv(ndev);
> +
> +	phy_power_off(rdev->serdes);
>  }
>  
>  static void rswitch_mac_link_up(struct phylink_config *config,
> @@ -1187,7 +1191,11 @@ static void rswitch_mac_link_up(struct phylink_config *config,
>  				phy_interface_t interface, int speed,
>  				int duplex, bool tx_pause, bool rx_pause)
>  {
> +	struct net_device *ndev = to_net_dev(config->dev);
> +	struct rswitch_device *rdev = netdev_priv(ndev);
> +
>  	/* Current hardware cannot change speed at runtime */
> +	phy_power_on(rdev->serdes);
>  }
>  
>  static const struct phylink_mac_ops rswitch_phylink_ops = {

This looks to me like it will break anyone using an in-band link,
where the link status comes from the PCS behind the series that
you're now powering down and up.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!