[U-Boot] [PATCH 2/2] net: phy: Add ability to program the ksz9031 skew values from the uboot env

[Stefan Roese]

On 11.02.2015 09:07, Joe Hershberger wrote:
>>>> I agree it would make more sense to pull these from devicetree - I'm
>>>> planning on adding that in a future patch. I thought it would be a good
>>>> idea to pull these values from the environment first, overriding the
>>>> devicetree (if present in the environment). This approach is helpful
>>>> during bringup & debug since it doesn't require one to change the
>>>> devicetree to try something quickly. I'm ok with any approach you think
>>>> would work for the community.
>>>
>>>
>>> You can do that with the 'mii' command as well I think, but I might be
> wrong.
>>
>>
>> Yes. For testing or board bringup this might really serve. Even though
> this setting via environment as proposed from Vince is more elegant and
> less hackish. And easier to adjust/tune for "normal users".
>>
>> The default values should come from the DT, once this is all in place.
> But I think that for initial board bringup / testing such a method, to
> override those values via environment variables can be quite helpful.
>>
>> Joe, whats your opinion on this?
>
> Do we really think this is a strong use-case?  This seem like the type of
> thing I would expect to tweak for testing through mii / mdio commands and
> then configure the device tree based on that.  This is pretty much a
> one-time thing for a given board it seems to me.
>
> If we really want a polished interface to it, we should define a
> sub-command / new command that phy drivers can implement.  I'm not sure an
> undiscoverable, un-"help"-able list of env vars will be apparent to users.
> Do you have a feeling for how close to universal any of these parameters
> are across phys?

No. But with your comments above (which make total sense), I tend to NAK 
this ability to configure the PHY skew timings via environment variables.

Thanks,
Stefan