linux-kernel - Re: [PATCH net-next v2 4/5] net-next: ethernet: mediatek: add device_node of GMAC pointing into the netdev instance

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Message-ID: <20170322181846.GN30655@lunn.ch>
Date:   Wed, 22 Mar 2017 19:18:46 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     sean.wang@...iatek.com
Cc:     f.fainelli@...il.com, vivien.didelot@...oirfairelinux.com,
        matthias.bgg@...il.com, robh+dt@...nel.org, mark.rutland@....com,
        devicetree@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        davem@...emloft.net, Landen.Chao@...iatek.com, keyhaede@...il.com,
        objelf@...il.com
Subject: Re: [PATCH net-next v2 4/5] net-next: ethernet: mediatek: add
 device_node of GMAC pointing into the netdev instance

On Tue, Mar 21, 2017 at 05:35:09PM +0800, sean.wang@...iatek.com wrote:
> From: Sean Wang <sean.wang@...iatek.com>
> 
> the patch adds the setup of the corresponding device node of GMAC into the
> netdev instance which could allow other modules such as DSA to find the
> instance through the node in dt-bindings using of_find_net_device_by_node()
> call.
> 
> Signed-off-by: Sean Wang <sean.wang@...iatek.com>
> ---
>  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> index c21ed99..84b09a4 100644
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> @@ -2323,6 +2323,8 @@ static int mtk_add_mac(struct mtk_eth *eth, struct device_node *np)
>  	eth->netdev[id]->ethtool_ops = &mtk_ethtool_ops;
>  
>  	eth->netdev[id]->irq = eth->irq[0];
> +	eth->netdev[id]->dev.of_node = np;
> +

Humm, O.K. This is not obvious, until you look at of_dev_node_match()
in net-sysfs.c.

Most Ethernet drivers don't set netdev.dev.of_node. But they do call
SET_NETDEV_DEV(), which sets netdev.dev.parent.

of_dev_node_match() first looks at netdev.dev.parent->of_node, and if that
does not match, then looks at netdev.dev.of_node.

For the mtk Ethernet driver, the parent is not going to work, because
of the sub devices. So netdev.dev.of_node does need to be set.

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew