[U-Boot] [PATCH v1 0/5]

[thomas.langer at lantiq.com]

Hello Stefano,

Stefano Babic wrote on 2013-09-02:

> Some phys have additional registers that are not covered
> by standard. Access to this registers can be done via
> specific sequence according to the phy datasheet.
> The driver for Micrel phy contains some additional function,
> that the board maintainer can call to tune the phy. However,
> these registers cannot be accessed with "mmdio" command.
> 
> Add calback to the phy API to allow to call the function
> for reading / writing extended registers with the mmdio command.
> 
> 

The basic mechanism used for the access is not specific to Micrel, it is defined 
in the IEEE standard [1], "Annex 22D: Clause 22 access to Clause 45 MMD registers"

A presentation for this can be found when you ask google for it [2]

[1]: IEEE Std 802.3-2008 (or 2012): http://standards.ieee.org/about/get/802/802.3.html
[2]: https://www.google.de/search?q=%22Clause+22+Access+to+Clause+45+Registers%22

So maybe it will be useful to have the access functions in the common phy lib?

I assume that most current PHYs have these method implemented,
as also some extended standard registers needs this.
For example, the EEE (Energy Efficient Ethernet) registers are located in this extended
register range.

Probably this can be extended in some follow-up patches, 
I just wanted to share my thoughts ;-)
I currently have not platform on my desk which uses phylib (and current code),
so I cannot provide a patch on my own, sorry.

Best Regards,
Thomas