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

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Message-ID: <20130523184028.GU31290@titan.lakedaemon.net>
Date:	Thu, 23 May 2013 14:40:28 -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 11:53:57AM -0600, Jason Gunthorpe wrote:
> On Thu, May 23, 2013 at 01:23:39PM -0400, Jason Cooper wrote:
> 
> > Shouldn't it rather be
> > 
> > 	compatible = "marvell,kirkwood-eth", "marvell,orion-eth";
> 
> Not sure about 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.
> 
> But there is a larger problem here then just this one bit.
> 
> The PSC1 register must be set properly for the board layout, and today
> we rely on the bootloader to set it. In fact, even with Sebastian's
> change the ethernet port won't work without bootloader
> intervention. The PortReset bit should also be cleared by the driver
> (and it is only present on some variants of this IP block,
> apparently).
> 
> We know that some Marvell SOC's wack the ethernet registers when they
> clock gate, and the flip of Clk125Bypass is another symptom of this
> general problem.
> 
> So, long term, the PSC1 must be fully set by the driver, based on DT
> information describing the board (eg RGMII/MII/1000Base-X [SFP] Phy
> type), and the layout of this register seems to vary on a SOC by SOC
> basis.
> 
> Thus, I think it is appropriate to call this variant of the eth IP
> 'marvell,kirkwood-eth' which indicates that the register block follows
> the kirkwood manual and the PSC1 register specifically has the
> kirkwood layout.

Ok, so mv643xx_eth would match both "marvell,orion-eth" and
"marvell,kirkwood-eth", then write to PSC1 iff it sees a node matching
"marvell,kirkwood-eth".  I'm not too keen on that, however, the matching
of the machine doesn't look to good, either.

Perhaps a better answer is to add a boolean, "marvell,kirkwood_psc1" and
check for that?

Or, marvell,psc1_reset = <0xWWXXYYZZ>;

> The question is what other Marvell SOCs have the same PSC1 layout as
> kirkwood?

I think marvell,psc1_reset = <>; gives us the most flexibility in
accurately describing the hardware.

thx,

Jason.
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