Message-ID: <20191112190957.nbfb6g2bxiipjnbi@lx-anielsen.microsemi.net>
Date:   Tue, 12 Nov 2019 20:09:57 +0100
From:   "Allan W. Nielsen" <allan.nielsen@...rochip.com>
To:     Vladimir Oltean <olteanv@...il.com>
CC:     Andrew Lunn <andrew@...n.ch>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        "David S. Miller" <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Joergen Andreasen <joergen.andreasen@...rochip.com>,
        Horatiu Vultur <horatiu.vultur@...rochip.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        netdev <netdev@...r.kernel.org>,
        Vladimir Oltean <vladimir.oltean@....com>
Subject: Re: [PATCH net-next 10/12] net: dsa: vitesse: move vsc73xx driver to
 a separate folder

The 11/12/2019 17:26, Vladimir Oltean wrote:
> External E-Mail
> 
> 
> On Tue, 12 Nov 2019 at 16:57, Allan W. Nielsen
> <allan.nielsen@...rochip.com> wrote:
> >
> > The 11/12/2019 15:50, Andrew Lunn wrote:
> > > External E-Mail
> > >
> > >
> > > > > > As there are no commonalities between the vsc73xx and felix drivers,
> > > > > > shouldn't you simply leave that one out and have felix in the existing
> > > > > > microchip folder?
> > > > > >
> > > > >
> > > > > I don't have a strong preference, although where I come from, all new
> > > > > NXP networking drivers are still labeled as "freescale" even though
> > > > > there is no code reuse. There are even less commonalities with
> > > > > Microchip (ex-Micrel, if I am not mistaken) KSZ switches than with the
> > > > > old vsc73xx. I'll let the ex-Vitesse people decide.
> > > > I'm on the same page as Alexandre here.
> > >
> > > Leaving them where they are makes maintenance easier. Fixes are easier
> > > to backport if things don't move around.
> > >
> > > > I think we should leave vsc73xx where it is already, and put the felix driver in
> > > > the drivers/net/ethernet/mscc/ folder where ocelot is already.
> > >
> > > Currently, all DSA drivers are in drivers/net/dsa. We do occasionally
> > > make changes over all DSA drivers at once, so it is nice they are all
> > > together. So i would prefer the DSA part of Felix is also there. But
> > > the core can be in drivers/net/ethernet/mscc/.
> > Ahh, my bad.
> >
> > In that case I do not have any strong feelings on this either.
> >
> > I should say that we are discussing to add support for a Ocelot VSC7511 as a DSA
> > driver. This one does not have an internal MIPS CPU.
> >
> > The vsc73xx, felix and the drivers in dsa/microchip does not share any
> > functionallity. Not in SW and not in HW.
> >
> > Maybe felix should just go directly into drivers/net/dsa/, and then if we add
> > support for VSC7511 then they can both live in drivers/net/dsa/ocelot/


A bit of background such that people outside NXP/MCHP has a better change to
follow and add to the discussion.

Ocelot is a family name covering 4 VSC parts (VSC7511-14), and a IP used by NXP
(VSC9959).

VSC7511-14 are all register compatible, it uses the same serdes etc.

VSC7511/12 are "unmanaged" meaning that they do not have an embedded CPU.

VSC7513/14 has an embedded MIPS CPU.

VSC9959 not the same core as VSC7511-14, it is a newer generation with more
features, it is not register compatible, but all the basic functionallity is
very similar VSC7511-14 which is why it can call into the
drivers/net/ethernet/mscc/ocelot.c file.

It is likely that NXP want to add more features in felix/VSC9959 which does not
exists in VSC7511-14.

> When the felix driver is going to support the vsc7511 ocelot switch
> through the ocelot core, it will be naming chaos.
I do not think a VSC7511 will be based on Felix, but it will relay on the
refacturing/restructuring you have done in Ocelot.

VSC7511 will use the same PCS and serdes settings as Ocelot (VSC7513/VSC7514)

> Maybe we need to clarify what "felix" means (at the moment it means VSC9959).
Yes.

> What if we just make it mean "DSA driver for Ocelot", and it supports both the
> VSC751x (Ocelot) and the VSC9959 (Felix) families?
I'm not too keen on using the felix name for that.

Here is my suggestion:

Drop the felix name and put it in drivers/net/dsa/ocelot_vsc9959* (this would be
my preference)

Or if you want the felix name put it in drivers/net/dsa/ocelot_felix*

Or if we want folders put it in drivers/net/dsa/ocelot/vsc9959*

When we get to it, we can add vsc7511/12 in drivers/net/dsa/ocelot_vsc7512*

To be consisten and clean up (my) earlier mistake we should rename the
drivers/net/ethernet/mscc/ocelot_board.c to
drivers/net/ethernet/mscc/ocelot_vsc7514.c (as it is really not board stuff, but
ocelot internal cpu stuff).

Andrew also pointed out that the stuff put into this file did not seem very
board related.

> Is anybody else instantiating the VSC9959 core, or close derivatives, except
> NXP LS1028A? If the answer is yes, are those other instantiations PCI devices,
> or something else?
Not what I'm aware of.

> I would appreciate if you could take a
> look through the probing part of patch 11/12 (the "felix_instance_tbl"
> part and felix-regs.c) and see if there are any naming changes I can
> make that would make it easier for you to fit in one more device.
Will do.

> Of course, I don't expect to make radical changes, you'd still need to do some
> refactoring if you decide to add your vsc7511, I just care that the
> refactoring doesn't change any current semantics.
The majority of the needed changes to add vsc7511 has been done by now ;-)

/Allan

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