linux-kernel - Re: [net-next PATCH] net: dsa: qca8k: make sure PAD0 MAC06 exchange is disabled

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Date:   Tue, 2 Nov 2021 20:26:55 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Ansuel Smith <ansuelsmth@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [net-next PATCH] net: dsa: qca8k: make sure PAD0 MAC06 exchange
 is disabled

On Tue, Nov 02, 2021 at 06:56:29PM +0100, Ansuel Smith wrote:
> Some device set MAC06 exchange in the bootloader. This cause some
> problem as we don't support this strange mode and we just set the port6
> as the primary CPU port. With MAC06 exchange, PAD0 reg configure port6
> instead of port0. Add an extra check and explicitly disable MAC06 exchange
> to correctly configure the port PAD config.
> 
> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> ---

Reviewed-by: Vladimir Oltean <olteanv@...il.com>

Since net-next has closed, please add

Fixes: 3fcf734aa482 ("net: dsa: qca8k: add support for cpu port 6")

and resend to the "net" tree.

>  drivers/net/dsa/qca8k.c | 8 ++++++++
>  drivers/net/dsa/qca8k.h | 1 +
>  2 files changed, 9 insertions(+)
> 
> Some comments here:
> Resetting the switch using the sw reg doesn't reset the port PAD
> configuration. I was thinking if it would be better to clear all the
> pad configuration but considering that the entire reg is set by phylink
> mac config, I think it's not necessary as the PAD related to the port will
> be reset anyway with the new values. Have a dirty configuration on PAD6
> doesn't cause any problem as we have that port disabled and it would be
> reset and configured anyway if defined.
> 
> diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
> index ea7f12778922..a429c9750add 100644
> --- a/drivers/net/dsa/qca8k.c
> +++ b/drivers/net/dsa/qca8k.c
> @@ -1109,6 +1109,14 @@ qca8k_setup(struct dsa_switch *ds)
>  	if (ret)
>  		return ret;
>  
> +	/* Make sure MAC06 is disabled */
> +	ret = qca8k_reg_clear(priv, QCA8K_REG_PORT0_PAD_CTRL,
> +			      QCA8K_PORT0_PAD_MAC06_EXCHANGE_EN);
> +	if (ret) {
> +		dev_err(priv->dev, "failed disabling MAC06 exchange");
> +		return ret;
> +	}
> +
>  	/* Enable CPU Port */
>  	ret = qca8k_reg_set(priv, QCA8K_REG_GLOBAL_FW_CTRL0,
>  			    QCA8K_GLOBAL_FW_CTRL0_CPU_PORT_EN);
> diff --git a/drivers/net/dsa/qca8k.h b/drivers/net/dsa/qca8k.h
> index e10571a398c9..128b8cf85e08 100644
> --- a/drivers/net/dsa/qca8k.h
> +++ b/drivers/net/dsa/qca8k.h
> @@ -34,6 +34,7 @@
>  #define   QCA8K_MASK_CTRL_DEVICE_ID_MASK		GENMASK(15, 8)
>  #define   QCA8K_MASK_CTRL_DEVICE_ID(x)			((x) >> 8)
>  #define QCA8K_REG_PORT0_PAD_CTRL			0x004
> +#define   QCA8K_PORT0_PAD_MAC06_EXCHANGE_EN		BIT(31)
>  #define   QCA8K_PORT0_PAD_SGMII_RXCLK_FALLING_EDGE	BIT(19)
>  #define   QCA8K_PORT0_PAD_SGMII_TXCLK_FALLING_EDGE	BIT(18)
>  #define QCA8K_REG_PORT5_PAD_CTRL			0x008
> -- 
> 2.32.0
>