14.07.2015 20:51, Florian Fainelli пишет:
On 14/07/15 10:13, Stas Sergeev wrote:
Currently the PHY management type is selected by the MAC driver arbitrary.
The decision is based on the presence of the "fixed-link" node and on a
will of the driver's authors.
This caused a regression recently, when mvneta driver suddenly started
to use the in-band status for auto-negotiation on fixed links.
It appears the auto-negotiation may not work when expected by the MAC driver.
Sebastien Rannou explains:
<< Yes, I confirm that my HW does not generate an in-band status. AFAIK, it's
a PHY that aggregates 4xSGMIIs to 1xQSGMII ; the MAC side of the PHY (with
inband status) is connected to the switch through QSGMII, and in this context
we are on the media side of the PHY. >>
https://lkml.org/lkml/2015/7/10/206
This patch introduces the new string property 'managed' that allows
the user to set the management type explicitly.
The supported values are:
"auto" - default. Uses either MDIO or nothing, depending on the presence
of the fixed-link node
"mdio" - use MDIO
"in-band-status" - use in-band status
"none" - use fixed-link description
I thought we agreed in the last thread that "mdio" was implied whenever
a proper PHY phandle to a device sitting on MDIO bus is used and that
"auto" did not make much sense unless we were also describing how to do
this auto-negotiation completely?
Exactly not:
---
If we would implement autoneg outside of the fixed-link,
then its semantic would likely be
autoneg = "mdio" | "in-band" | "off"
Right, if auto-negotiation was defined outside of fixed-link, that is
indeed how I would also specify this.
---
That's why I implemented it the way you see.
But as you changed your mind, I'll remove "mdio".
As mentioned below, "mdio" is redundant with finding a "phy-handle",
and "auto" is not specific enough to be useful to a consumer of this
information.
I prefer to keep "auto", as otherwise we'll have the default
value (when the option is not specified) never achievable
when the option _is_ specified, which is probably not very
good. But I can remove "none" instead, leaving only
"in-band-status" and "auto". Ok?
Of course one can propose to completely ignore that option
in presence of MDIO, but I wonder why not to allow for
example to opt for in-band status even if you have MDIO?
So if we want this option to play nicely with MDIO, as opposed
to being entirely overridden, then "auto" still makes sense IMO.
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