linux-kernel - Re: [PATCH 2/2] net: mv643xx_eth: proper initialization for Kirkwood SoCs

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Message-ID: <20130523172339.GQ31290@titan.lakedaemon.net>
Date:	Thu, 23 May 2013 13:23:39 -0400
From:	Jason Cooper <jason@...edaemon.net>
To:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Cc:	Andrew Lunn <andrew@...n.ch>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	linuxppc-dev@...ts.ozlabs.org, David Miller <davem@...emloft.net>,
	Lennert Buytenhek <buytenh@...tstofly.org>,
	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
Subject: Re: [PATCH 2/2] net: mv643xx_eth: proper initialization for
 Kirkwood SoCs

On Thu, May 23, 2013 at 11:11:12AM -0600, Jason Gunthorpe wrote:
> On Thu, May 23, 2013 at 12:01:11PM -0400, Jason Cooper wrote:
> > > > +	/* Kirkwood resets some registers on gated clocks. Especially
> > > > +	 * CLK125_BYPASS_EN must be cleared but is not available on
> > > > +	 * all other SoCs/System Controllers using this driver.
> > > > +	 */
> > > > +	if (of_machine_is_compatible("marvell,kirkwood"))
> > > > +		wrlp(mp, PORT_SERIAL_CONTROL1,
> > > > +		     rdlp(mp, PORT_SERIAL_CONTROL1) & ~CLK125_BYPASS_EN);
> > > 
> > > of_machine_is_compatible seems heavy handed, I would expect this to be
> > > based on the compatible string of the ethernet node itself, not the
> > > machine??
> > 
> > Is there a model number variation between IP that needs this and IP that
> > doesn't?  If not, I'm fine with of_machine_is_compatible().
> 
> Well the name 'mv643xx' is a family of system controller SOC's
> from ages ago, it seems reasonble to continue the trend and label the
> IP variations with the SOC name:
> 
>  compatible = "marvell,kirwood,ethernet", "marvell,mv643xx_eth"

Shouldn't it rather be

	compatible = "marvell,kirkwood-eth", "marvell,orion-eth";

I'm inclined to go with of_machine_is_compatible() since the only
concrete difference we know is that the tweak is needed on kirkwood and
nowhere else.

If we had an errata, or a datasheet saying specifically flavor X needs
this and none other does, then we could trigger on the ethernet node
compatible string or a boolean in the node.  But we don't have that...

thx,

Jason.
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