netdev - Re: [PATCH net-next] net: pcs: tse: port to pcs-lynx

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Message-ID: <Y+ai3zHMUCDcxqxP@lunn.ch>
Date:   Fri, 10 Feb 2023 21:02:39 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Vladimir Oltean <vladimir.oltean@....com>
Cc:     Maxime Chevallier <maxime.chevallier@...tlin.com>,
        davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, thomas.petazzoni@...tlin.com,
        Jakub Kicinski <kuba@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        linux-arm-kernel@...ts.infradead.org,
        Ioana Ciornei <ioana.ciornei@....com>
Subject: Re: [PATCH net-next] net: pcs: tse: port to pcs-lynx

On Fri, Feb 10, 2023 at 09:31:59PM +0200, Vladimir Oltean wrote:
> On Fri, Feb 10, 2023 at 08:09:49PM +0100, Maxime Chevallier wrote:
> > When submitting the initial driver for the Altera TSE PCS, Russell King
> > noted that the register layout for the TSE PCS is very similar to the
> > Lynx PCS. The main difference being that TSE PCS's register space is
> > memory-mapped, whereas Lynx's is exposed over MDIO.
> > 
> > Convert the TSE PCS to reuse the whole logic from Lynx, by allowing
> > the creation of a dummy MDIO bus, and a dummy MDIO device located at
> > address 0 on that bus. The MAC driver that uses this PCS must provide
> > callbacks to read/write the MMIO.
> > 
> > Also convert the Altera TSE MAC driver to this new way of using the TSE
> > PCS.
> > 
> > Signed-off-by: Maxime Chevallier <maxime.chevallier@...tlin.com>
> > ---
> >  drivers/net/ethernet/altera/altera_tse.h      |   2 +-
> >  drivers/net/ethernet/altera/altera_tse_main.c |  50 ++++-
> >  drivers/net/pcs/Kconfig                       |   4 +
> >  drivers/net/pcs/pcs-altera-tse.c              | 194 +++++++-----------
> >  include/linux/pcs-altera-tse.h                |  22 +-
> >  5 files changed, 142 insertions(+), 130 deletions(-)
> 
> The glue layer is larger than the duplicated PCS code? :(

I was wondering if the glue could actually be made generic. The kernel
has a number of reasonably generic MMIO device drivers, which are just
given an address range and assume a logical mapping.

Could this be made into a generic MDIO MMIO bus driver, which just
gets configured with a base address, and maybe a stride between
registers?

	Andrew