linux-kernel - Re: [PATCH net-next v3 3/6] net: hisilicon: add support for hisi

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Message-ID: <20240220135512.GN40273@kernel.org>
Date: Tue, 20 Feb 2024 13:55:12 +0000
From: Simon Horman <horms@...nel.org>
To: forbidden405@...look.com
Cc: Yisen Zhuang <yisen.zhuang@...wei.com>,
	Salil Mehta <salil.mehta@...wei.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh+dt@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>, Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH net-next v3 3/6] net: hisilicon: add support for
 hisi_femac core on Hi3798MV200

On Tue, Feb 20, 2024 at 03:57:38AM +0800, Yang Xiwen via B4 Relay wrote:
> From: Yang Xiwen <forbidden405@...look.com>
> 
> Register the sub MDIO bus if it is found. Also implement the internal
> PHY reset procedure as needed.
> 
> Note it's unable to put the MDIO bus node outside of MAC controller
> (i.e. at the same level in the parent bus node). Because we need to
> control all clocks and resets in FEMAC driver due to the phy reset
> procedure. So the clocks can't be assigned to MDIO bus device, which is
> an essential resource for the MDIO bus to work.
> 
> No backward compatibility is maintained since the only existing
> user(Hi3516DV300) has not received any updates from HiSilicon for about
> 8 years already. And till today, no mainline dts for this SoC is found.
> It seems unlikely that there are still existing mainline Hi3516DV300
> users. The effort to maintain the old binding seems gain a little.
> 
> Signed-off-by: Yang Xiwen <forbidden405@...look.com>
> ---
>  drivers/net/ethernet/hisilicon/hisi_femac.c | 77 +++++++++++++++++++++++------
>  1 file changed, 61 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/net/ethernet/hisilicon/hisi_femac.c b/drivers/net/ethernet/hisilicon/hisi_femac.c

..

> @@ -826,15 +844,34 @@ static int hisi_femac_drv_probe(struct platform_device *pdev)
>  						 priv->phy_reset_delays,
>  						 DELAYS_NUM);
>  		if (ret)
> -			goto out_disable_clk;
> +			goto out_free_netdev;
>  		hisi_femac_phy_reset(priv);
>  	}
>  
> +	// Register the optional MDIO bus
> +	for_each_available_child_of_node(node, mdio_np) {
> +		if (of_node_name_prefix(mdio_np, "mdio")) {
> +			priv->mdio_pdev = of_platform_device_create(mdio_np, NULL, dev);
> +			of_node_put(mdio_np);
> +			if (!priv->mdio_pdev) {
> +				dev_err(dev, "failed to register MDIO bus device\n");
> +				ret = -ENODEV;
> +				goto out_free_netdev;
> +			}
> +			mdio_registered = true;
> +			break;
> +		}
> +		of_node_put(mdio_np);

Sorry for not noticing this earlier.

I think that of_node_put() only needs to be called in the
case of terminating the loop (via break, goto, return, etc...).
But should not be called otherwise (when the loop cycles) as
for_each_available_child_of_node() calls of_node_put().

Flagged by Coccinelle.

> +	}
> +
> +	if (!mdio_registered)
> +		dev_warn(dev, "MDIO subnode not found. This is usually a bug.\n");
> +
>  	phy = of_phy_get_and_connect(ndev, node, hisi_femac_adjust_link);
>  	if (!phy) {
>  		dev_err(dev, "connect to PHY failed!\n");
>  		ret = -ENODEV;
> -		goto out_disable_clk;
> +		goto out_unregister_mdio_bus;
>  	}
>  
>  	phy_attached_print(phy, "phy_id=0x%.8lx, phy_mode=%s\n",

..