Re: [PATCH net-next v5 1/7] net: phylink: add PHY_F_RXC_ALWAYS_ON to PHY dev flags

From: Andrew Lunn <andrew@lunn.ch>
To: Romain Gantois <romain.gantois@bootlin.com>
Cc: "Russell King" <linux@armlinux.org.uk>,
	"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>,
	"Alexandre Torgue" <alexandre.torgue@foss.st.com>,
	"Jose Abreu" <joabreu@synopsys.com>,
	"Maxime Coquelin" <mcoquelin.stm32@gmail.com>,
	"Clément Léger" <clement.leger@bootlin.com>,
	"Maxime Chevallier" <maxime.chevallier@bootlin.com>,
	"Miquel Raynal" <miquel.raynal@bootlin.com>,
	"Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
	netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org,
	linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH net-next v5 1/7] net: phylink: add PHY_F_RXC_ALWAYS_ON to PHY dev flags
Date: Mon, 4 Mar 2024 14:36:33 +0100	[thread overview]
Message-ID: <95968657-04a3-4558-9ecb-92d7721592ff@lunn.ch> (raw)
In-Reply-To: <20240301-rxc_bugfix-v5-1-8dac30230050@bootlin.com>

On Fri, Mar 01, 2024 at 04:34:58PM +0100, Romain Gantois wrote:
> From: Russell King <linux@armlinux.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@armlinux.org.uk>
> [rgantois: commit log]
> Signed-off-by: Romain Gantois <romain.gantois@bootlin.com>

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

    Andrew