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

From: Maxime Chevallier <maxime.chevallier@bootlin.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: Vladimir Oltean <vladimir.oltean@nxp.com>,
	davem@davemloft.net, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, thomas.petazzoni@bootlin.com,
	Jakub Kicinski <kuba@kernel.org>,
	Eric Dumazet <edumazet@google.com>,
	Paolo Abeni <pabeni@redhat.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Russell King <linux@armlinux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	Ioana Ciornei <ioana.ciornei@nxp.com>
Subject: Re: [PATCH net-next] net: pcs: tse: port to pcs-lynx
Date: Tue, 21 Feb 2023 08:34:12 +0100	[thread overview]
Message-ID: <20230221083412.5e11db13@pc-7.home> (raw)
In-Reply-To: <Y+ai3zHMUCDcxqxP@lunn.ch>

Hi Vlad, Andrew,

On Fri, 10 Feb 2023 21:02:39 +0100
Andrew Lunn <andrew@lunn.ch> wrote:

> 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@bootlin.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?

That would be ideal, I'll spin a new series prorotyping this, indeed
that can be interesting for other devices.

Thanks for the review,

Maxime

> 	Andrew

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