Re: [RFC PATCHv2 0/4] Add DT support for fixed PHYs

Hi

quoted

Hello,

Here is a second version of the patch set that adds a Device Tree
binding and the related code to support fixed PHYs. Marked as RFC,
this patch set is obviously not intended for merging in 3.12.

Since the first version, the changes have been:

 * Instead of using a 'fixed-link' property inside the Ethernet device
   DT node, with a fairly cryptic succession of integer values, we now
   use a PHY subnode under the Ethernet device DT node, with explicit
   properties to configure the duplex, speed, pause and other PHY
   properties.

 * The PHY address is automatically allocated by the kernel and no
   longer visible in the Device Tree binding.

 * The PHY device is created directly when the network driver calls
   of_phy_connect_fixed_link(), and associated to the PHY DT node,
   which allows the existing of_phy_connect() function to work,
   without the need to use the deprecated of_phy_connect_fixed_link().

The things I am not entirely happy with yet are:

 * The PHY ID is hardcoded to 0xdeadbeef. Ideally, it should be a
   properly reserved vendor/device identifier, but it isn't clear how
   to get one allocated for this purpose.

 * The fixed_phy_register() function in drivers/net/phy/fixed.c has
   some OF references. So ideally, I would have preferred to put this
   code in drivers/of/of_mdio.c, but to call get_phy_device(), we need
   a reference to the mii_bus structure that represents the fixed MDIO
   bus.

 * There is some error management missing in fixed_phy_register(), but
   it can certainly be added easily. This RFC is meant to sort out the
   general idea.

+1 for the general idea. This really looks good now. I've not much more
to say. Maybe someone from the devicetree corner has a few words for the
binding?

I tested the whole series with an I.MX6D board with the FEC driver:
fec 2188000.ethernet eth0: Freescale FEC PHY driver [Generic PHY]
(mii_bus:phy_addr=fixed-0:00, irq=-1)

For me binding looks nice and I hope to see this patch series in 3.13.

Tested-by: Christian Gmeiner <redacted>
--
Christian Gmeiner, MSc
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