From: Andrew Lunn <andrew@lunn.ch>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Fabio Estevam <festevam@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>, Sandor Yu <sandor.yu@nxp.com>,
Heiner Kallweit <hkallweit1@gmail.com>,
Vladimir Oltean <vladimir.oltean@nxp.com>,
Bruno Thomsen <bruno.thomsen@gmail.com>,
Florian Fainelli <f.fainelli@gmail.com>
Subject: Re: [PATCH v3 1/2] dt-bindings: gpio: 74x164: Introduce the 'registers-default' property
Date: Thu, 7 Jan 2021 15:33:55 +0100 [thread overview]
Message-ID: <X/cb0xhqTHV3eBdA@lunn.ch> (raw)
In-Reply-To: <CACRpkdYtjXMOv+G3_hXAiS4J51FKC4kcuDCmqr_kivuh61udPw@mail.gmail.com>
> Indeed, but I don't understand why the phy in this example does not
> have a compatible string?
Normally, PHYs can be enumerated on the bus, in the same way USB and
PCI devices can be enumerated. The device itself then tells you what
it is campatible with, in the same way PCI and USB does. Having a
compatible string is then detrimental, because people get it wrong,
device tree says one thing, the device itself says something else,
which do we trust? There are also boards where different series of
have populated with different pin compatible PHYs. Enumeration just
works, having a compatible would be a problem.
But, there are some PHYs which you cannot enumerate, e.g they do not
respond to MDIO while held in reset, or the silicon is buggy and has
an invalid ID. In those cases, a compatible should be listed with the
correct PHY ID.
Andrew
next prev parent reply other threads:[~2021-01-07 14:34 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-30 21:49 [PATCH v3 1/2] dt-bindings: gpio: 74x164: Introduce the 'registers-default' property Fabio Estevam
2020-12-30 21:49 ` [PATCH v3 2/2] " Fabio Estevam
2021-01-05 15:40 ` Linus Walleij
2021-01-05 15:34 ` [PATCH v3 1/2] dt-bindings: " Linus Walleij
2021-01-07 12:16 ` Fabio Estevam
2021-01-07 14:17 ` Linus Walleij
2021-01-07 14:33 ` Andrew Lunn [this message]
2021-01-07 14:25 ` Andrew Lunn
2021-01-07 14:38 ` Fabio Estevam
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