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

[Ben Warren]

Michael Trimarchi wrote:
> Hi,
> ----- Messaggio originale -----
>   
>> Da: Haavard Skinnemoen <hskinnemoen at atmel.com>
>> A: Michael Trimarchi <trimarchimichael at yahoo.it>
>> Cc: Michael Schwingen <rincewind at discworld.dascon.de>; u-boot-users at lists.sourceforge.net
>> Inviato: Venerdì 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