netdev - Re: [PATCH net-next v2 3/3] net: phy: mscc: coma mode disabled for VSC8514

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Date:   Mon, 15 Feb 2021 21:08:34 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Bjarni Jonasson <bjarni.jonasson@...rochip.com>,
        Andrew Lunn <andrew@...n.ch>,
        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>,
        Vladimir Oltean <vladimir.oltean@....com>,
        Ioana Ciornei <ioana.ciornei@....com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        UNGLinuxDriver <UNGLinuxDriver@...rochip.com>,
        Steen Hegelund <steen.hegelund@...rochip.com>
Subject: Re: [PATCH net-next v2 3/3] net: phy: mscc: coma mode disabled for
 VSC8514

On 15.02.2021 17:58, 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.")
> ---
> v1 -> v2:
>   Modified coma mode config 
>   Changed net to net-next
> 
>  drivers/net/phy/mscc/mscc.h      |  3 +++
>  drivers/net/phy/mscc/mscc_main.c | 16 ++++++++++++++++
>  2 files changed, 19 insertions(+)
> 
> diff --git a/drivers/net/phy/mscc/mscc.h b/drivers/net/phy/mscc/mscc.h
> index 9d8ee387739e..2b70ccd1b256 100644
> --- a/drivers/net/phy/mscc/mscc.h
> +++ b/drivers/net/phy/mscc/mscc.h
> @@ -160,6 +160,9 @@ enum rgmii_clock_delay {
>  #define MSCC_PHY_PAGE_TR		  0x52b5 /* Token ring registers */
>  #define MSCC_PHY_GPIO_CONTROL_2	  14
>  
> +#define MSCC_PHY_COMA_MODE		  0x2000 /* input(1) / output(0) */
> +#define MSCC_PHY_COMA_OUTPUT		  0x1000 /* value to output */
> +
>  /* Extended Page 1 Registers */
>  #define MSCC_PHY_CU_MEDIA_CRC_VALID_CNT	  18
>  #define VALID_CRC_CNT_CRC_MASK		  GENMASK(13, 0)
> diff --git a/drivers/net/phy/mscc/mscc_main.c b/drivers/net/phy/mscc/mscc_main.c
> index 03181542bcb7..29302ccf7e7b 100644
> --- a/drivers/net/phy/mscc/mscc_main.c
> +++ b/drivers/net/phy/mscc/mscc_main.c
> @@ -1520,6 +1520,21 @@ 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_unlock_mdio_bus(phydev);
> +	/* Enable output (mode=0) and write zero to it */
> +	phy_modify_paged(phydev, MSCC_PHY_PAGE_EXTENDED_GPIO,
> +			 MSCC_PHY_GPIO_CONTROL_2,
> +			 MSCC_PHY_COMA_MODE | MSCC_PHY_COMA_OUTPUT, 0);
> +	phy_lock_mdio_bus(phydev);

The temporary unlock is a little bit hacky. Better do:
vsc85xx_phy_write_page(MSCC_PHY_PAGE_EXTENDED_GPIO)
__phy_modify()
vsc85xx_phy_write_page(default page)

Alternatively we could add __phy_modify_paged(). But this may not
be worth the effort for now.

> +}
> +
>  static int vsc8584_config_init(struct phy_device *phydev)
>  {
>  	struct vsc8531_private *vsc8531 = phydev->priv;
> @@ -2604,6 +2619,7 @@ 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);
>