Re: [RFC PATCH net-next v3 4/5] net: dsa: qca8k: flag QCA8337 internal CPU PHYs for SmartSpeed

[Andrew Lunn]

> I'm open to selecting the workaround through DT, so that it is enabled
> only on boards known to need it. What I can document at this point is
> the PHY-to-PHY connection, the reproducible boot failure and the effect
> of disabling SmartSpeed. I have not established whether the cause is
> the board's electrical design or something else.

This is tricky. I can understand not wanting to say the board design
is broken without strong evidence. But a DT property is about
hardware. Maybe word it something like ... when the hardware uses an
on board PHY-to-PHY connection, without cable, SmartSpeed has been
seen to incorrectly performed a downshift. There have not been any
reports of a traditional hardware designs, using a cable, having this
issue.

> Would that be sufficient justification for a DT property, with the
> underlying cause left open in the commit message? If so, would you
> prefer a generic PHY property to disable downshift, or a
> Qualcomm-specific property for this workaround?

Also tricky. What we don't want is other developers trying to abuse
this to turn it into a configuration option, rather than a hardware
property. So i don't think it should be a generic property. Lets make
it a qualcomm specific property. I would also put 'workaround' in the
property name, again making it clear this is not intended to be used
for configuration.

    Andrew