netdev - Re: Need help with mdiobus

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Message-ID: <20161014040641.GE5822@lunn.ch>
Date:   Fri, 14 Oct 2016 06:06:41 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Timur Tabi <timur@...eaurora.org>
Cc:     netdev@...r.kernel.org
Subject: Re: Need help with mdiobus_register and phy

On Thu, Oct 13, 2016 at 06:15:39PM -0500, Timur Tabi wrote:
> I need help with a program I've discovered with my driver
> (ethernet/qualcomm/emac/) that occurs in the following process:
> 
> 1. Load the driver
> 1a. Driver calls mdiobus_register (see emac_phy_config), which calls
> mdiobus_scan(), which calls get_phy_device()
> 1b. get_phy_device() performs MDIO bus operations, which means the
> bus and the external phy need to be active.
> 2. Bring up the interface
> 3. Bring down the interface.  This calls phy_disconnect() which
> calls phy_detach() which calls phy_suspend().  This puts the
> external phy to sleep.
> 4. Unload the driver
> 5. Re-load the driver.
> 5a. Driver calls mdiobus_register again, but this time the call to
> get_phy_device() fails because the external phy is asleep and does
> not respond to MDIO transactions.

Hi Timur

Normally, a sleeping PHY does respond to MDIO. Otherwise, how do you
wake it?

So i assume this phy has some other means to wake it. What is this
means?

      Andrew