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

[Vince Bridgers <vbridger@opensource.altera.com>]

Hi Marek!

> We already do this kind of a programming in board/altera/socfpga/socfpga.c
> in board_phy_config(), don't we ?

Yes, good point. This patch series is a first in some upcoming patches to make this better. The Linux implementation uses devicetree settings to set the skews, so if we were to follow that same model the code in socfpga.c would become deprecated in favor of setting the skews through the phy driver and subsequently removed. That way other users could take advantage of this through devicetree. The other problem with the current implementation is the skew values are part specific - we set the actual register values in the environment when it would be better to use a skewed time value (in +/- picoseconds). 

> Also, see [1], once I apply this, the DT support (not DM) for SoCFPGA will
> become mandatory. Won't it make more sense to pull these values from the
> DT instead of poluting the board environment with those please ?

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. 

I'm ok with whatever the community decides considering my rationale above. 

All the best!

Vince
vbridger at opensource.altera.com