Re: [PATCH 1/2] net: ethernet: nb8800: Do not apply TX delay at MAC level

On 11/09/2016 06:03 PM, Florian Fainelli wrote:

On 11/09/2016 05:02 AM, Sebastian Frias wrote:

quoted

On 11/04/2016 05:49 PM, Måns Rullgård wrote:

quoted

quoted

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But when doing so, both the Atheros 8035 and the Aurora NB8800 drivers
will apply the delay.

I think a better way of dealing with this is that both, PHY and MAC
drivers exchange information so that the delay is applied only once.

Exchange what information? The PHY device interface (phydev->interface)
conveys the needed information for both entities.

There doesn't seem to be any consensus among the drivers regarding where
the delay should be applied.  Since only a few drivers, MAC or PHY, act
on this property, most combinations still work by chance.  It is common
for boards to set the delay at the PHY using external config pins so no
software setup is required (although I have one Sigma based board that
gets this wrong).  I suspect if drivers/net/ethernet/broadcom/genet were
used with one of the four PHY drivers that also set the delay based on
this DT property, things would go wrong.

Exactly, what about a patch like (I can make a formal submission, even
merge it with the patch discussed in this thread, consider this a RFC):

I really don't see a point in doing this when we can just clarify what
phydev->interface does and already have the knowledge that we need
without introducing additional flags in the phy driver.

Ok, so who can clarify what "phydev->interface" does, especially in the
context of this discussion?

What happens when a TX delay must be applied and:
  - both the PHY and the MAC support the delay
  - only the PHY supports the delay
  - only the MAC supports the delay

Best regards,

Sebastian