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From: Andrew Lunn <andrew@lunn.ch>
To: Florian Fainelli <florian.fainelli@broadcom.com>
Cc: netdev@vger.kernel.org, hkallweit1@gmail.com,
	ansuelsmth@gmail.com, rmk+kernel@armlinux.org.uk,
	Doug Berger <opendmb@gmail.com>,
	Broadcom internal kernel review list 
	<bcm-kernel-feedback-list@broadcom.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net] net: bcmgenet: Ensure MDIO unregistration has clocks enabled
Date: Thu, 22 Jun 2023 17:36:40 +0200	[thread overview]
Message-ID: <533872e1-b323-4bca-aacc-4d3cfbed53bd@lunn.ch> (raw)
In-Reply-To: <20230622103107.1760280-1-florian.fainelli@broadcom.com>

On Thu, Jun 22, 2023 at 03:31:07AM -0700, Florian Fainelli wrote:
> With support for Ethernet PHY LEDs having been added, while
> unregistering a MDIO bus and its child device liks PHYs there may be
> "late" accesses to the MDIO bus. One typical use case is setting the PHY
> LEDs brightness to OFF for instance.
> 
> We need to ensure that the MDIO bus controller remains entirely
> functional since it runs off the main GENET adapter clock.

So this clock is enabled in bcmgenet_open() and disabled in
bcmgenet_close(). The assumption being, the MDIO bus is only used when
the interface is up.

How does this work when there is an MDIO based switch attached? I had
similar problems with the FEC and mv88e6xxx. DSA would try to talk to
the switch with the master interface down, and MDIO would time out. I
needed to add runtime PM support to the MDIO bus ops.

       Andrew

  reply	other threads:[~2023-06-22 15:37 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-22 10:31 Florian Fainelli
2023-06-22 15:36 ` Andrew Lunn [this message]
2023-06-22 15:50   ` Florian Fainelli
2023-06-22 19:14     ` Andrew Lunn
2023-06-24  2:00 ` patchwork-bot+netdevbpf

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