netdev - Re: [PATCH v5 02/14] net: pch_gbe: Pull PHY GPIO handling out of Minnow code

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Date:   Sat, 17 Feb 2018 14:50:22 -0800
From:   Paul Burton <paul.burton@...s.com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     <netdev@...r.kernel.org>, Hassan Naveed <hassan.naveed@...s.com>,
        "Matt Redfearn" <matt.redfearn@...s.com>,
        "David S . Miller" <davem@...emloft.net>,
        <linux-mips@...ux-mips.org>
Subject: Re: [PATCH v5 02/14] net: pch_gbe: Pull PHY GPIO handling out of
 Minnow code

Hi Andrew,

On Sat, Feb 17, 2018 at 11:29:33PM +0100, Andrew Lunn wrote:
> On Sat, Feb 17, 2018 at 12:10:25PM -0800, Paul Burton wrote:
> > The MIPS Boston development board uses the Intel EG20T Platform
> > Controller Hub, including its gigabit ethernet controller, and requires
> > that its RTL8211E PHY be reset much like the Minnow platform. Pull the
> > PHY reset GPIO handling out of Minnow-specific code such that it can be
> > shared by later patches.
> 
> Hi Paul
> 
> I'm i right in saying the driver currently supports the Atheros AT8031
> PHY? The same phy which is supported in drivers/net/phy/at803x.c?

It looks like the driver does contain some code relating to that PHY,
but it's not the one I'm using with the MIPS Boston board - there we
have a Realtek RTL8211E (as mentioned in the commit message) which is
working fine alongside this pch_gbe driver too.

> If so, i think you are doing this all wrong.

Note that this is a driver which is already in mainline, and I didn't
write it. Claiming that *I* am doing this all wrong is a bit of a
stretch - all this patch does is make small changes to some existing
code, which only tangentially relates to a PHY driver, such that it
ceases to be specific to a single platform.

> You would be much better off throwing away pch_gbe_phy.c and write a
> proper MDIO driver. You then get the PHY driver for free, and the MDIO
> code could will handle your GPIO for you, in the standardised way.

Even if that is true, rewriting the driver's PHY handling would be a
very separate change to the changes this series make which allow this
driver to work on a platform besides the Minnowboard. The *only* thing
this series does relating to the PHY is allow the reset GPIO to be
handled properly - rewriting the existing PHY handling is beyond it's
scope.

Note that I do have various cleanups to the driver beyond this series
which I intend to submit after it is functional for my system[1], so I
am not saying that I don't care about improving the driver. But please,
let's do one thing at a time.

Thanks,
    Paul

[1] https://git.linux-mips.org/cgit/paul/linux.git/log/?h=up417-boston-eth-cleanup