linux-kernel - Re: [PATCH net v1 3/3] net: phy: mscc: coma mode disabled for VSC8514

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Date:   Fri, 12 Feb 2021 16:32:42 +0000
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Bjarni Jonasson <bjarni.jonasson@...rochip.com>
CC:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Antoine Tenart <atenart@...nel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Ioana Ciornei <ioana.ciornei@....com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Steen Hegelund <steen.hegelund@...rochip.com>
Subject: Re: [PATCH net v1 3/3] net: phy: mscc: coma mode disabled for VSC8514

On Fri, Feb 12, 2021 at 03:06:43PM +0100, Bjarni Jonasson wrote:
> The 'coma mode' (configurable through sw or hw) provides an
> optional feature that may be used to control when the PHYs become active.
> The typical usage is to synchronize the link-up time across
> all PHY instances. This patch releases coma mode if not done by hardware,
> otherwise the phys will not link-up.
> 
> Signed-off-by: Steen Hegelund <steen.hegelund@...rochip.com>
> Signed-off-by: Bjarni Jonasson <bjarni.jonasson@...rochip.com>
> Fixes: e4f9ba642f0b ("net: phy: mscc: add support for VSC8514 PHY.")
> ---
>  drivers/net/phy/mscc/mscc_main.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/net/phy/mscc/mscc_main.c b/drivers/net/phy/mscc/mscc_main.c
> index 7546d9cc3abd..0600b592618b 100644
> --- a/drivers/net/phy/mscc/mscc_main.c
> +++ b/drivers/net/phy/mscc/mscc_main.c
> @@ -1418,6 +1418,18 @@ static void vsc8584_get_base_addr(struct phy_device *phydev)
>  	vsc8531->addr = addr;
>  }
>  
> +static void vsc85xx_coma_mode_release(struct phy_device *phydev)
> +{
> +	/* The coma mode (pin or reg) provides an optional feature that
> +	 * may be used to control when the PHYs become active.
> +	 * Alternatively the COMA_MODE pin may be connected low
> +	 * so that the PHYs are fully active once out of reset.
> +	 */
> +	__phy_write(phydev, MSCC_EXT_PAGE_ACCESS, MSCC_PHY_PAGE_EXTENDED_GPIO);
> +	__phy_write(phydev, MSCC_PHY_GPIO_CONTROL_2, 0x0600);
> +	__phy_write(phydev, MSCC_EXT_PAGE_ACCESS, MSCC_PHY_PAGE_STANDARD);

Can you please do:
	phy_write_paged(phydev, MSCC_PHY_PAGE_EXTENDED_GPIO,
			MSCC_PHY_GPIO_CONTROL_2, 0x0600);

And can you please provide some definitions for what 0x0600 is?
My reference manual says that:

Bit 13:
COMA_MODE output enable (active low)
Bit 12:
COMA_MODE output data
Bit 11:
COMA_MODE input data
Bit 10:
Reserved
Bit 9:
Tri-state enable for LEDs

0x600 is BIT(10) | BIT(9). But BIT(10) is reserved. Sure this is correct?

> +}
> +
>  static int vsc8584_config_init(struct phy_device *phydev)
>  {
>  	struct vsc8531_private *vsc8531 = phydev->priv;
> @@ -2610,6 +2622,7 @@ static int vsc8514_config_init(struct phy_device *phydev)
>  		ret = vsc8514_config_host_serdes(phydev);
>  		if (ret)
>  			goto err;
> +		vsc85xx_coma_mode_release(phydev);
>  	}
>  
>  	phy_unlock_mdio_bus(phydev);
> -- 
> 2.17.1
>