[PATCH 2/6] ARM: mvebu: Add proper pin muxing on Globalscale Mirabox board

[Andrew Lunn]

On Fri, Aug 08, 2014 at 03:21:56PM -0300, Ezequiel Garcia wrote:
> On 08 Aug 07:12 PM, Andrew Lunn wrote:
> > On Fri, Aug 08, 2014 at 12:18:52PM -0300, Ezequiel Garcia wrote:
> > > This commit adds the required pin muxing for the network interfaces and
> > > the MDIO interface to be properly initialized. For instance, this makes
> > > it possible for a bootloader to initialize and access the network interfaces.
> > > 
> > > Signed-off-by: Ezequiel Garcia <ezequiel.garcia at free-electrons.com>
> > > ---
> > >  arch/arm/boot/dts/armada-370-mirabox.dts | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > > 
> > > diff --git a/arch/arm/boot/dts/armada-370-mirabox.dts b/arch/arm/boot/dts/armada-370-mirabox.dts
> > > index 097df7d8..c745256 100644
> > > --- a/arch/arm/boot/dts/armada-370-mirabox.dts
> > > +++ b/arch/arm/boot/dts/armada-370-mirabox.dts
> > > @@ -91,6 +91,8 @@
> > >  			};
> > >  
> > >  			mdio {
> > > +				pinctrl-0 = <&mdio_pins>;
> > > +				pinctrl-names = "default";
> > >  				phy0: ethernet-phy at 0 {
> > >  					reg = <0>;
> > >  				};
> > > @@ -100,11 +102,15 @@
> > >  				};
> > >  			};
> > >  			ethernet at 70000 {
> > > +				pinctrl-0 = <&ge0_pins>;
> > > +				pinctrl-names = "default";
> > 
> > Hi Ezequiel
> > 
> > Could you put these one level higher in the DT hierarchy? i.e. once in
> > armada-370.dtsi and not in every board .dts file?
> > 
> 
> Are you sure that's the correct approach?
> 
> As explained on the cover letter, these MAC MPP mux are not required in the
> SGMII case. Moreover, this is not the only way to wire the MAC0 and MAC1
> controllers, so I even considered pushing down the pinmux to the dts files!

Hi Ezequiel

At least at the moment, it seems like RGMII is the norm, and SGMII is
the exception. So having the default as RGMII probably makes
sense. Boards which don't require it can then override this in there
.dts file. If we see this changes with time, we can swap it around.

> The devicetree location of the pinmux is something that still confuses me,
> so I'm more than open to directions here.

Patch #1 comment is not really correct. It defines a number of pin
configuration nodes. These nodes can then be used via phandles.  What
might help is naming these differently. Name them
ge[01]_rgmii_pins. It is then clear when they should be used. You can
also add ge[0]_sgmii_pins, which would be an empty set. You can then
use ge[01]_rgmii_pins as the default in armada-370.dtsi and override
them with ge[0]_sgmii_pins for the 370 RD.

Experience from Kirkwood is that it also has multiple ways to wire up
MAC0 and MAC1, but in practice, nobody ever does. And if they did, it
can be overridden in the .dts file.

    Andrew