On Monday, August 22, 2016 2:04:49 PM CEST Martin Blumenstingl wrote:

On Mon, Aug 22, 2016 at 1:55 PM, Arnd Bergmann [off-list ref] wrote:

quoted

On Saturday, August 20, 2016 11:35:35 AM CEST Martin Blumenstingl wrote:

quoted

+- reg: The first register range should be the one of the DWMAC
+       controller. The second range is is for the Amlogic specific
+       configuration (for example the PRG_ETHERNET register range
+       on Meson8b and newer)

...

quoted

+Example for GXBB:
+       ethmac: ethernet at c9410000 {
+               compatible = "amlogic,meson-gxbb-dwmac", "snps,dwmac";
+               reg = <0x0 0xc9410000 0x0 0x10000>,
+                       <0x0 0xc8834540 0x0 0x8>;

The address "0xc8834540" suggests that this is part of a larger register
range that is used for various things, i.e. a "syscon" type of device.

You are right, these are part of the cbus range (which is already
defined in meson-gxbb.dtsi)

quoted

How about making this a syscon reference rather than a "reg" address?

The first version of my patch ([0]) used
syscon_regmap_lookup_by_phandle. Maybe I did it wrong (and I should
have passed the cbus syscon-node instead of defining a new one just
for the 2x32bit PRG_ETHERNET registers).
I am perfectly fine with either way - however it seems that some other
dwmac glue implementations are also using a second set of resources
(that doesn't automatically make it "correct" though).

It really depends on the kind of SoC. Some may have a suboptimal
binding, on some others there may be a distinct register area that
just contains a few additional registers for the dwmac.

	Arnd