netdev - Re: [PATCH net v2 9/9] net: ethernet: mediatek: fix error handling inside mtk_mdio

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Date:   Mon, 29 Aug 2016 15:15:58 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     sean.wang@...iatek.com
Cc:     john@...ozen.org, davem@...emloft.net, nbd@...nwrt.org,
        netdev@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        keyhaede@...il.com
Subject: Re: [PATCH net v2 9/9] net: ethernet: mediatek: fix error handling
 inside mtk_mdio_init

On Mon, Aug 29, 2016 at 01:03:23PM +0800, sean.wang@...iatek.com wrote:
> From: Sean Wang <sean.wang@...iatek.com>
> 
> return -ENODEV if no child is found in MDIO bus.

Hi Sean

Why is it an error not to have any children on the bus?

Say i have a fibre optical module connected to the MAC. It is unlikely
to have an MII interface, so i would not list it on the bus. With this
change, if i have the mdio-bus node in my device tree, i don't get a
working system. Without this change, it simply does not instantiate
the MDIO device, and returns without an error.

I think this patch should be dropped, or maybe a comment adding, why
the current code returns 0 at this point.

    Andrew

> 
> Signed-off-by: Sean Wang <sean.wang@...iatek.com>
> Acked-by: John Crispin <john@...ozen.org>
> ---
>  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> index f741c6a..e48b2a4 100644
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> @@ -304,7 +304,7 @@ static int mtk_mdio_init(struct mtk_eth *eth)
>  	}
>  
>  	if (!of_device_is_available(mii_np)) {
> -		ret = 0;
> +		ret = -ENODEV;
>  		goto err_put_node;
>  	}
>  
> -- 
> 1.9.1
>