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From: Andrew Lunn <andrew@lunn.ch>
To: "Adam Rudziński" <adam.rudzinski@arf.net.pl>
Cc: robh+dt@kernel.org, frowand.list@gmail.com, f.fainelli@gmail.com,
	netdev <netdev@vger.kernel.org>
Subject: Re: drivers/of/of_mdio.c needs a small modification
Date: Sat, 29 Aug 2020 00:28:46 +0200	[thread overview]
Message-ID: <20200828222846.GA2403519@lunn.ch> (raw)
In-Reply-To: <c8b74845-b9e1-6d85-3947-56333b73d756@arf.net.pl>

Hi Adam

> If kernel has to bring up two Ethernet interfaces, the processor has two
> peripherals with functionality of MACs (in i.MX6ULL these are Fast Ethernet
> Controllers, FECs), but uses a shared MDIO bus, then the kernel first probes
> one MAC, enables clock for its PHY, probes MDIO bus tryng to discover _all_
> PHYs, and then probes the second MAC, and enables clock for its PHY. The
> result is that the second PHY is still inactive during PHY discovery. Thus,
> one Ethernet interface is not functional.

What clock are you talking about? Do you have the FEC feeding a 50MHz
clock to the PHY? Each FEC providing its own clock to its own PHY? And
are you saying a PHY without its reference clock does not respond to
MDIO reads and hence the second PHY does not probe because it has no
reference clock?

	  Andrew

       reply	other threads:[~2020-08-28 22:28 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <c8b74845-b9e1-6d85-3947-56333b73d756@arf.net.pl>
2020-08-28 22:28 ` Andrew Lunn [this message]
2020-08-28 22:34   ` drivers/of/of_mdio.c needs a small modification Adam Rudziński
2020-08-28 22:53     ` Andrew Lunn
2020-08-28 23:14       ` Adam Rudziński
2020-08-29  3:29         ` Florian Fainelli
2020-08-29  8:15           ` Adam Rudziński
2020-08-29 15:15             ` Andrew Lunn
2020-08-29 15:37               ` Adam Rudziński
2020-08-29 16:00                 ` Andrew Lunn
2020-08-29 18:01                   ` Adam Rudziński
2020-08-29 23:16                     ` Andrew Lunn
2020-08-30 20:47                       ` Adam Rudziński

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