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Date:   Thu, 1 Jun 2023 13:14:27 -0700
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Subject: Re: [PATCH 2/2] net: phy: realtek: Add optional external PHY clock
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To:     Andrew Lunn <andrew@lunn.ch>,
        Detlev Casanova <detlev.casanova@collabora.com>
Cc:     linux-kernel@vger.kernel.org,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>, netdev@vger.kernel.org,
        devicetree@vger.kernel.org
References: <20230531150340.522994-1-detlev.casanova@collabora.com>
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 <7bde15a1-08fe-4036-9256-b13280340b6b@lunn.ch>
From:   Florian Fainelli <f.fainelli@gmail.com>
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On 6/1/23 12:37, Andrew Lunn wrote:
>> I'm not sure about this. Isn't the clock still necessary when suspended for
>> things like wake on lan ?
> 
> Yes, but the PHY should know if its a WoL source, and not disable its
> own clock. There is some support for this in phylib, and Florian has
> also reworked it recently for Broadcom PHYs.

If you want to have the PHY driver have a chance to disable the clock if 
Wake-on-LAN is disabled and therefore conserve power, you should set 
PHY_ALWAYS_CALL_SUSPEND in the phy_driver::flags and in the 
suspend/resume functions do something like:

suspend:
	/* last step after all registers are accessed */
	if (!phydev->wol_enabled)
		clk_disable_unprepare()
resume:
	/* first step before registers are accessed */
	if (!phydev->wol_enabled)
		clk_prepare_enable()

The flag is necessary to ensure that the PHY driver's suspend function 
will be called. The resume will be called regardless of Wake-on-LAN 
being enabled or not.
-- 
Florian