From: Andrew Lunn <andrew@lunn.ch>
To: Paolo Abeni <pabeni@redhat.com>
Cc: Heiner Kallweit <hkallweit1@gmail.com>,
Neil Armstrong <neil.armstrong@linaro.org>,
Russell King - ARM Linux <linux@armlinux.org.uk>,
David Miller <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>,
Kevin Hilman <khilman@baylibre.com>,
Jerome Brunet <jbrunet@baylibre.com>,
Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"open list:ARM/Amlogic Meson..."
<linux-amlogic@lists.infradead.org>
Subject: Re: [PATCH net-next] net: phy: meson-gxl: support more G12A-internal PHY versions
Date: Tue, 17 Jan 2023 14:30:19 +0100 [thread overview]
Message-ID: <Y8ai6+oaaP0KwkAY@lunn.ch> (raw)
In-Reply-To: <699f6ee109b3a72b2b377f42a78705f47d4a77b9.camel@redhat.com>
> > The PHY compatible string in DT is the following in all cases:
> > compatible = "ethernet-phy-id0180.3301"
This form of compatible has two purposes.
1) You cannot read the PHY ID register during MDIO bus enumeration,
generally because you need to turn on GPIOs, clocks, regulators etc,
which the MDIO/PHY core does not know how to do.
2) The PHY has bad values in its ID registers, typically because the
manufactures messed up.
If you have a compatible like this, the ID registers are totally
ignored by Linux, and the ID is used to find the driver and tell the
driver exactly which of the multiple devices it supports it should
assume the device is.
So you should use this from of compatible with care. You can easily
end up thinking you have a different PHY to what you actually have,
which could then result in wrong erratas being applied etc, or even
the wrong driver being used.
Andrew
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next prev parent reply other threads:[~2023-01-17 13:31 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-15 15:19 [PATCH net-next] net: phy: meson-gxl: support more G12A-internal PHY versions Heiner Kallweit
2023-01-15 16:57 ` Andrew Lunn
2023-01-15 17:09 ` Heiner Kallweit
2023-01-15 18:43 ` Neil Armstrong
2023-01-15 19:42 ` Anand Moon
2023-01-15 20:38 ` Heiner Kallweit
2023-01-17 12:04 ` Paolo Abeni
2023-01-17 13:30 ` Andrew Lunn [this message]
2023-01-17 14:51 ` Heiner Kallweit
2023-01-20 9:55 ` Jerome Brunet
2023-01-19 22:42 ` Heiner Kallweit
2023-01-20 10:01 ` Jerome Brunet
2023-01-20 10:22 ` Heiner Kallweit
2023-01-20 10:52 ` Heiner Kallweit
2023-01-20 12:48 ` Jerome Brunet
2023-01-19 22:56 ` [PATCH net-next] net: mdio: mux-meson-g12a: use devm_clk_get_enabled to simplify the code Heiner Kallweit
2023-01-20 10:14 ` Jerome Brunet
2023-01-23 14:50 ` patchwork-bot+netdevbpf
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