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Date:   Sat, 27 Aug 2022 20:38:34 +0200
From:   Andrew Lunn <andrew@lunn.ch>
To:     Oleksij Rempel <o.rempel@pengutronix.de>
Cc:     Heiner Kallweit <hkallweit1@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Russell King <linux@armlinux.org.uk>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Jonathan Corbet <corbet@lwn.net>,
        kernel test robot <lkp@intel.com>, kernel@pengutronix.de,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        devicetree@vger.kernel.org, linux-doc@vger.kernel.org,
        David Jander <david@protonic.nl>,
        Luka Perkov <luka.perkov@sartura.hr>,
        Robert Marko <robert.marko@sartura.hr>
Subject: Re: [PATCH net-next v3 6/7] ethtool: add interface to interact with
 Ethernet Power Equipment
Message-ID: <Ywpkqt2pDmpzXWWn@lunn.ch>
References: <20220827051033.3903585-1-o.rempel@pengutronix.de>
 <20220827051033.3903585-7-o.rempel@pengutronix.de>
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> +static int pse_set_pse_config(struct net_device *dev,
> +			      struct netlink_ext_ack *extack,
> +			      struct nlattr **tb)
> +{
> +	struct phy_device *phydev = dev->phydev;
> +	struct pse_control_config config = {};
> +	int ret;
> +
> +	if (!tb[ETHTOOL_A_PODL_PSE_ADMIN_CONTROL])
> +		return -EINVAL;

I would make use of extack here, and report what is missing.

> +
> +	config.admin_cotrol = nla_get_u8(tb[ETHTOOL_A_PODL_PSE_ADMIN_CONTROL]);

It would be good to have some basic validation here, make sure user
space has passed a reasonable value.

You should also define what 0 and
ETHTOOL_A_PODL_PSE_ADMIN_CONTROL_UNKNOWN means here when passed in. In
future, there could be additional things which could be configured, so
struct pse_control_config gets additional members.
ETHTOOL_A_PODL_PSE_ADMIN_CONTROL appears to be mandatory, you return
-EVINAL if missing, so if you don't want to change it, but change some
other new thing, maybe 0 should be passed here? And the driver should
not consider it an error?  ETHTOOL_A_PODL_PSE_ADMIN_CONTROL_UNKNOWN
however seems invalid and so should be rejected here?

	Andrew