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

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Message-ID: <20130523160111.GP31290@titan.lakedaemon.net>
Date:	Thu, 23 May 2013 12:01:11 -0400
From:	Jason Cooper <jason@...edaemon.net>
To:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Cc:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	Andrew Lunn <andrew@...n.ch>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	linux-kernel@...r.kernel.org,
	Lennert Buytenhek <buytenh@...tstofly.org>,
	netdev@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	David Miller <davem@...emloft.net>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/2] net: mv643xx_eth: proper initialization for
 Kirkwood SoCs

Sebastian,

On Wed, May 22, 2013 at 02:16:07PM -0600, Jason Gunthorpe wrote:
> On Wed, May 22, 2013 at 10:04:02PM +0200, Sebastian Hesselbarth wrote:
> 
> > Ethernet controllers found on Kirkwood SoCs not only suffer from loosing
> > MAC address register contents on clock gating but also some important
> > registers are reset to values that would break ethernet. This patch
> 
> FWIW, we found that the bootloader has to write to PSC1, the driver
> doesn't work with the power on/reset value of the register. So I think
> it is safe to assume that all kirkwood bootloaders alter the value.
> 
> Our systems write the value 0x00638488 to PSC1.
> 
> I looked at patching mv643xx_eth, but ran into the same complexity you
> did, it isn't clear what variants of this IP block have the
> register/etc.
> 
> > +	/* 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().

thx,

Jason.
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