U-Boot PHY_MSCC vs PHY_VITESSE

[Mathew McBride]

Hi Tom,

On Tue, Sep 30, 2025, at 8:43 AM, Tom Rini wrote:
> Hey all,
> 
> As part of working on "allyesconfig" support I ran into the following
> problem. Both drivers/net/phy/mscc.c and drivers/net/phy/vitesse.c
> implement support for the VSC8584 PHY. The vitesse.c driver is much
> older and only had VSC8584 support added for a specific Freescale
> Layerscape platform whereas mscc.c is modern and been updated with
> newer PHYs as well. And we need one driver to support this phy, not two.
> I am inclined to remove support from vitesse.c. However, only 4
> platforms use the PHY_MSCC driver and everyone else uses PHY_VITESSE.
> 

At the moment mscc.c in U-Boot does not implement the particular PHY model (VSC8514) that we use. This Quad GbE PHY was on a number on Freescale/NXP QorIQ (PPC & Arm) dev boards. Until 2019 Freescale/NXP was selling a licensed version of this chip ("F104S8A").

The Linux version of mscc.c does support these PHYs, so we can bring across from that driver.
However, many PHYs in this family have complicated errata workarounds, and the VSC8514 is no exception.

I have made some attempts to "port" the mscc.c support for VSC8514 (erratas included) before, but it's errata workaround method does not seem to work as reliably in U-Boot as it does under Linux.

(I also have my own version of vitesse.c which implements the errata workaround for VSC8514, derived directly from Microchips own SDK sources. Unfortunately it's too messy to submit to U-Boot, but it has worked reliably for many years) 

> I'm cc'ing all of the board maintainers (other than PowerPC platforms)
> that use PHY_VITESEE today to see what their feedback is on which way to
> go here. I'm ignoring PowerPC because that can just stay on the
> PHY_VITESSE driver based on timing of changes in git log.
> 
I'm in favor (as far as board/traverse/ten64 goes) of migrating to mscc.c, it is just a matter of finding the time to sit down and implement support for the PHY I need (VSC8514).

Best Regards,
Matt

> -- 
> Tom
> 
> 
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