RE: [EXT] Re: [PATCH net-next 5/6] arm64: dts: marvell: mcbin: enable the fourth network interface

[Stefan Chulski]

> -----Original Message-----
> From: Marcin Wojtas [mailto:mw@xxxxxxxxxxxx]
> Sent: Monday, January 01, 2018 12:18 PM
> To: Russell King - ARM Linux <linux@xxxxxxxxxxxxxxx>
> Cc: Stefan Chulski <stefanc@xxxxxxxxxxx>; Thomas Petazzoni
> <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>; Andrew Lunn <andrew@xxxxxxx>;
> Florian Fainelli <f.fainelli@xxxxxxxxx>; Yan Markman
> <ymarkman@xxxxxxxxxxx>; Jason Cooper <jason@xxxxxxxxxxxxxx>; netdev
> <netdev@xxxxxxxxxxxxxxx>; Antoine Tenart <antoine.tenart@free-
> electrons.com>; linux-kernel@xxxxxxxxxxxxxxx; kishon@xxxxxx; Nadav Haklai
> <nadavh@xxxxxxxxxxx>; MiquÃl Raynal <miquel.raynal@xxxxxxxxxxxxxxxxxx>;
> Gregory ClÃment <gregory.clement@xxxxxxxxxxxxxxxxxx>; David S. Miller
> <davem@xxxxxxxxxxxxx>; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; Sebastian
> Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
> Subject: [EXT] Re: [PATCH net-next 5/6] arm64: dts: marvell: mcbin: enable the
> fourth network interface
> 
> External Email
> 
> ----------------------------------------------------------------------
> Hi Russell,
> 
> 2017-12-30 18:31 GMT+01:00 Russell King - ARM Linux
> <linux@xxxxxxxxxxxxxxx>:
> > Hi Marcin,
> >
> > On Sat, Dec 30, 2017 at 05:34:23PM +0100, Marcin Wojtas wrote:
> >> Yes, I already split the series and will send first one right away. I
> >> will be followed by MDIO bus / PHY handling proposal, including the
> >> bits related to phylink. I'm looking forward to your opinion on that
> >> once sent.
> >
> > I'm looking forward to the patches. :)
> >
> >> This my understanding of how the PP2 HW works in terms of signalling
> >> the link interrupt:
> >>
> >> The full in-band management, similar to mvneta is supported only in
> >> the SGMII mode (1G, not sure how it looks like in 2.5G mode). Such
> >> handling is not yet implemented in the mvpp2.c
> >>
> >> 10G:
> >> The XGMII MAC (XLG) is capable of generating link status change
> >> interrupt upon information provided from the reconciliation layer
> >> (RS) of the interface.
> >>
> >> 2.5G/1G SGMII:
> >> Apart from the in-band management, the MAC is also capable of
> >> generating IRQ during link-status change.
> >>
> >> 1G RGMII:
> >> I was a bit surprised, but checked on my own - the link change IRQ
> >> can be generated here as well.
> >>
> >> In addition to above the clause 22 PHYs can be automatically polled
> >> via SMI bus and provide complete information about link status,
> >> speed, etc., reflecting it directly in GMAC status registers.
> >> However, this feature had to be disabled, in order not to conflict
> >> with SW PHY management of the phylib.
> >>
> >> Stefan, is above correct?
> >
> > This sounds very much like mvneta's 'managed = "in-band"' mode.
> 
> Indeed. RGMII MAC behaves same way, although it shouldn't be named as 'in-
> band' to be on par with the specifications. Anyway - this one is rather a stub for
> being able to work with ACPI, so once the MDIO bus works there, this will be
> out of any concerns.

Hi Marcin,

This is correct.
"in-band" supported only for SGMII mode.
IRQ link interrupt depend on "in-band"' auto negation only if "in-band"' enabled.
But IRQ link interrupt could be triggered with "in-band", "out-band" or with specific fixed speed/duplex/flow_contol.

Best Regards.