netdev - Re: [PATCH v2 08/12] net: ethernet: stmmac: stm32: support the phy-supply regulator binding

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Date: Thu, 28 Sep 2023 19:53:08 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Christophe Roullier <christophe.roullier@...s.st.com>
Cc: "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>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Richard Cochran <richardcochran@...il.com>,
	Jose Abreu <joabreu@...opsys.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>, netdev@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 08/12] net: ethernet: stmmac: stm32: support the
 phy-supply regulator binding

> +static int phy_power_on(struct stm32_dwmac *bsp_priv, bool enable)

I find this function name confusing, since 50% of the time it does not
actually power the PHY on. You never call it with anything other than
a static true/false value. So it might was well be two functions,
phy_power_on() and phy_power_off().

> +{
> +	int ret;
> +	struct device *dev = bsp_priv->dev;
> +
> +	if (!bsp_priv->regulator)
> +		return 0;
> +
> +	if (enable) {
> +		ret = regulator_enable(bsp_priv->regulator);
> +		if (ret)
> +			dev_err(dev, "fail to enable phy-supply\n");

Not all PHYs are usable in 0 picoseconds. You probably want a delay
here. Otherwise the first few accesses to it might not work.

      Andrew