[U-Boot-Users] [PATCH] Add support for Generic PHY in macb

Ben Warren
2008-02-26T01:30:13Z

Michael Trimarchi wrote:
> Hi,
> ----- Messaggio originale -----
>
>> Da: Haavard Skinnemoen <hskinnemoen@atmel.com>
>> A: Michael Trimarchi <trimarchimichael@yahoo.it>
>> Cc: Michael Schwingen <rincewind@discworld.dascon.de>; u-boot-users at lists.sourceforge.net
>> Inviato: Venerd? 22 febbraio 2008, 17:08:56
>> Oggetto: Re: [U-Boot-Users] [PATCH] Add support for Generic PHY in macb
>>
>> On Fri, 22 Feb 2008 16:02:13 +0000 (GMT)
>> Michael Trimarchi wrote:
>>
>>
>>>> In any case, the dm9161a PHY in question does implement MDIO, so it
>>>> really should work without any modifications.
>>>>
>>>>
>>> Maybe we can add the for cycle like in linux to check the phy addr?
>>>
>> Yes, we could do that. But it comes with its own share of problems --
>> some boards have a too weak pull-up (or none at all) on the MDIO line,
>> so the probing code sometimes thinks it has found a whole bunch of
>> PHYs...
>>
>> Haavard
>>
>>
> But the u-boot user may to choice to use the automatic detection, based on
> phy_id mask and stop the search on the first one, or somenthing like this.
>
> Michael
>
I don't follow why you'd want to do this. As Andy, Haavard and others
have pointed out, you can't probe for PHY addresses because quite often
multiple ports will share an MDIO bus, and also it's unreliable at
best. Anybody who writes U-boot code needs to know the details of his
or her board, and PHY addresses are always fixed in hardware. There may
be some reason to make them dynamic, but I can't imagine why.

regards,
Ben