netdev - Re: Need help with mdiobus

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Date:   Fri, 14 Oct 2016 07:39:48 -0500
From:   Timur Tabi <timur@...eaurora.org>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     netdev@...r.kernel.org
Subject: Re: Need help with mdiobus_register and phy

Andrew Lunn wrote:
> Please can you tell us what PHY which is, and how it is put to sleep
> and woken up.

It's the at803x driver.

http://lxr.free-electrons.com/source/drivers/net/phy/at803x.c

It goes to sleep in its at803x_suspend() function, which is called by 
phy_suspend().

There is a corresponding at803x_resume().  The problem is that this is 
not called by mdiobus_register().  I'm guessing that mdiobus_register() 
assumes that the phy is awake.

It seems like a catch-22.  mdiobus_register() assumes that the phy is 
awake, but you can't wake up the phy until after you call 
mdiobus_register().

> If the PHY cannot be woken up using MDIO, then maybe you need to look
> at the mdio bus reset call?

I looked at that, but it won't work because there is no phydev when the 
reset function is called:

http://lxr.free-electrons.com/source/drivers/net/phy/mdio_bus.c#L328

It's the same catch-22.

-- 
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