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

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Date:   Thu, 5 Oct 2023 13:21:38 +0200
From:   Christophe ROULLIER <christophe.roullier@...s.st.com>
To:     Andrew Lunn <andrew@...n.ch>
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


On 9/28/23 19:53, Andrew Lunn wrote:
>> +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().

Hi,

I wanted to keep same implementation of all others Ethernet glues 
(dwmac-rk.c ...) to be consistent.

>> +{
>> +	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

You're right I will add a delay.

Thanks

Christophe