netdev - Re: [PATCH net-next v5 1/7] net: phylink: add PHY_F_RXC_ALWAYS

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Message-ID: <95968657-04a3-4558-9ecb-92d7721592ff@lunn.ch>
Date: Mon, 4 Mar 2024 14:36:33 +0100
From: Andrew Lunn <andrew@...n.ch>
To: Romain Gantois <romain.gantois@...tlin.com>
Cc: Russell King <linux@...linux.org.uk>,
	Heiner Kallweit <hkallweit1@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Jose Abreu <joabreu@...opsys.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Clément Léger <clement.leger@...tlin.com>,
	Maxime Chevallier <maxime.chevallier@...tlin.com>,
	Miquel Raynal <miquel.raynal@...tlin.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH net-next v5 1/7] net: phylink: add PHY_F_RXC_ALWAYS_ON to
 PHY dev flags

On Fri, Mar 01, 2024 at 04:34:58PM +0100, Romain Gantois wrote:
> From: Russell King <linux@...linux.org.uk>
> 
> Some MAC controllers (e.g. stmmac) require their connected PHY to
> continuously provide a receive clock signal. This can cause issues in two
> cases:
> 
>   1. The clock signal hasn't been started yet by the time the MAC driver
>      initializes its hardware. This can make the initialization fail, as in
>       the case of the rzn1 GMAC1 driver.
>   2. The clock signal is cut during a power saving event. By the time the
>      MAC is brought back up, the clock signal is still not active since
>      phylink_start hasn't been called yet. This brings us back to case 1.
> 
> If a PHY driver reads this flag, it should ensure that the receive clock
> signal is started as soon as possible, and that it isn't brought down when
> the PHY goes into suspend.
> 
> Signed-off-by: Russell King <linux@...linux.org.uk>
> [rgantois: commit log]
> Signed-off-by: Romain Gantois <romain.gantois@...tlin.com>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew