[PATCHv4 3/6] ARM: dts: Add initial LS1021A TWR board dts support

-----Original Message-----
From: Arnd Bergmann [mailto:arnd at arndb.de]
Sent: Wednesday, September 24, 2014 5:36 PM
To: Lu Jingchang-B35083
Cc: Guo Shawn-R65073; mark.rutland at arm.com; linux-arm-
kernel at lists.infradead.org; devicetree at vger.kernel.org; Lu Chen-B46807; Fu
Chao-B44548
Subject: Re: [PATCHv4 3/6] ARM: dts: Add initial LS1021A TWR board dts
support

On Wednesday 24 September 2014 05:47:53 Jingchang Lu wrote:

quoted

The ethernet device nodes already have the phy-handle properties to

their mdio nodes.

quoted

The alias for PHY nodes here is:
  The ethernet has two kind of PHY interface, one is SGMII, and the
other is RGMII, The selection is done by the reset configuration
word(RCW), so Phy-handle properties should be change properly to
reflecting the PHY interface selection. This is done by fixing up dtb
in u-boot before booting the kernel. Thus the alias for PHY nodes is

added here for fdt finding the PHY nodes easily.

Ok, I see. I thought that this was what the labels in the dtb were
supposed to be used for. Can't you do the same thing in u-boot by using a
label as opposed to the alias?

IIRC you should be able to add an additional label like

+&mdio0 {
+       enet1_sgmii_phy: sgmii_phy0: ethernet-phy at 0 {
+               reg = <0x0>;
+       };

and then use libfdt to find the node through that, rather than through the
alias. I don't know how things are handled on other platforms, but I think
that was how it was initially thought up when we introduced the fdt format
on PowerPC.

Arnd

We also do the phy-handle fixup on our PowerPC platform based on the aliases,
and so I adopt the same way to make these fixup consistent between SoCs.
And the u-boot fdt fixup code base on the aliases has been upstreamed, so may
we keep this aliases unchanged?

BTW, find a node by alias is easily, could you give me some clue on finding a node
by a label directly, Thanks.


Best Regards,
Jingchang