netdev - Re: [PATCH net-next v1 1/1] net: phy: ax88772a: fix lost pause advertisement configuration

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Date:   Fri, 24 Jun 2022 11:11:33 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>
Cc:     Lukas Wunner <lukas@...ner.de>, linux-kernel@...r.kernel.org,
        kernel@...gutronix.de, netdev@...r.kernel.org
Subject: Re: [PATCH net-next v1 1/1] net: phy: ax88772a: fix lost pause
 advertisement configuration

I forgot to add PHY maintainers. CCing Andrew and Heiner.

On Fri, Jun 24, 2022 at 09:55:58AM +0200, Oleksij Rempel wrote:
> In case of asix_ax88772a_link_change_notify() workaround, we run soft
> reset which will automatically clear MII_ADVERTISE configuration. The
> PHYlib framework do not know about changed configuration state of the
> PHY, so we need to save and restore all needed configuration registers.
> 
> Fixes: dde258469257 ("net: usb/phy: asix: add support for ax88772A/C PHYs")
> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> ---
>  drivers/net/phy/ax88796b.c | 37 ++++++++++++++++++++++++++++++++++++-
>  1 file changed, 36 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/phy/ax88796b.c b/drivers/net/phy/ax88796b.c
> index 457896337505..6971d0196917 100644
> --- a/drivers/net/phy/ax88796b.c
> +++ b/drivers/net/phy/ax88796b.c
> @@ -18,6 +18,11 @@ MODULE_DESCRIPTION("Asix PHY driver");
>  MODULE_AUTHOR("Michael Schmitz <schmitzmic@...il.com>");
>  MODULE_LICENSE("GPL");
>  
> +struct asix_context {
> +	u16 bmcr;
> +	u16 advertise;
> +};
> +
>  /**
>   * asix_soft_reset - software reset the PHY via BMCR_RESET bit
>   * @phydev: target phy_device struct
> @@ -83,13 +88,43 @@ static int asix_ax88772a_read_status(struct phy_device *phydev)
>  	return 0;
>  }
>  
> +/* save relevant PHY registers to private copy */
> +static void asix_context_save(struct phy_device *phydev,
> +			      struct asix_context *context)
> +{
> +	context->bmcr = phy_read(phydev, MII_BMCR);
> +	context->advertise = phy_read(phydev, MII_ADVERTISE);
> +}
> +
> +/* restore relevant PHY registers from private copy */
> +static void asix_context_restore(struct phy_device *phydev,
> +				 const struct asix_context *context)
> +{
> +	u16 bmcr = context->bmcr;
> +
> +	phy_write(phydev, MII_ADVERTISE, context->advertise);
> +
> +	/* after all settings are restored, restart autoneg */
> +	if (phydev->autoneg == AUTONEG_ENABLE)
> +		bmcr |= BMCR_ANRESTART;
> +
> +	phy_write(phydev, MII_BMCR, bmcr);
> +}
> +
>  static void asix_ax88772a_link_change_notify(struct phy_device *phydev)
>  {
>  	/* Reset PHY, otherwise MII_LPA will provide outdated information.
>  	 * This issue is reproducible only with some link partner PHYs
>  	 */
> -	if (phydev->state == PHY_NOLINK && phydev->drv->soft_reset)
> +	if (phydev->state == PHY_NOLINK && phydev->drv->soft_reset) {
> +		struct asix_context context;
> +
> +		asix_context_save(phydev, &context);
> +
>  		phydev->drv->soft_reset(phydev);
> +
> +		asix_context_restore(phydev, &context);
> +	}
>  }
>  
>  static struct phy_driver asix_driver[] = {
> -- 
> 2.30.2
> 
> 
> 

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