Re: [PATCH v3 net-next 12/14] dt-bindings: net: dsa: ocelot: add ocelot-ext documentation

Colin Foster
2022-10-05T15:44:26Z

On Wed, Oct 05, 2022 at 10:03:04AM +0200, Krzysztof Kozlowski wrote:
> On 05/10/2022 02:08, Colin Foster wrote:
> > Hi Krzysztof,
> >
> > On Tue, Oct 04, 2022 at 01:19:33PM +0200, Krzysztof Kozlowski wrote:
> >> On 26/09/2022 02:29, Colin Foster wrote:
> >>> The ocelot-ext driver is another sub-device of the Ocelot / Felix driver
> >>> system, which currently supports the four internal copper phys.
> >>>
> >>> Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
> > ...
> >>> + # Ocelot-ext VSC7512
> >>> + - |
> >>> + spi {
> >>> + soc@0 {
> >>
> >> soc in spi is a bit confusing.
> >>
> >> Does it even pass the tests? You have unit address but no reg.
> >
> > I omitted those from the documentation. Rob's bot is usually quick to
> > alert me when I forgot to run dt_binding_check and something fails
> > though. I'll double check, but I thought everything passed.
> >
> >>
> >>> + compatible = "mscc,vsc7512";
> >>
> >>
> >>> + #address-cells = <1>;
> >>> + #size-cells = <1>;
> >>> +
> >>> + ethernet-switch@0 {
> >>> + compatible = "mscc,vsc7512-switch";
> >>> + reg = <0 0>;
> >>
> >> 0 is the address on which soc bus?
> >
> > This one Vladimir brought up as well. The MIPS cousin of this chip
> > is the VSC7514. They have exactly (or almost exactly) the same hardware,
> > except the 7514 has an internal MIPS while the 7512 has an 8051.
> >
> > Both chips can be controlled externally via SPI or PCIe. This is adding
> > control for the chip via SPI.
> >
> > For the 7514, you can see there's an array of 20 register ranges that
> > all get mmap'd to 20 different regmaps.
> >
> > (Documentation/devicetree/bindings/net/mscc,vsc7514-switch.yaml)
> >
> > switch@1010000 {
> > compatible = "mscc,vsc7514-switch";
> > reg = <0x1010000 0x10000>,
> > <0x1030000 0x10000>,
> > <0x1080000 0x100>,
> > <0x10e0000 0x10000>,
> > <0x11e0000 0x100>,
> > <0x11f0000 0x100>,
> > <0x1200000 0x100>,
> > <0x1210000 0x100>,
> > <0x1220000 0x100>,
> > <0x1230000 0x100>,
> > <0x1240000 0x100>,
> > <0x1250000 0x100>,
> > <0x1260000 0x100>,
> > <0x1270000 0x100>,
> > <0x1280000 0x100>,
> > <0x1800000 0x80000>,
> > <0x1880000 0x10000>,
> > <0x1040000 0x10000>,
> > <0x1050000 0x10000>,
> > <0x1060000 0x10000>,
> > <0x1a0 0x1c4>;
> > reg-names = "sys", "rew", "qs", "ptp", "port0", "port1",
> > "port2", "port3", "port4", "port5", "port6",
> > "port7", "port8", "port9", "port10", "qsys",
> > "ana", "s0", "s1", "s2", "fdma";
> >
> >
> > The suggestion was to keep the device trees of the 7512 and 7514 as
> > similar as possible, so this will essentially become:
> > switch@71010000 {
> > compatible = "mscc,vsc7512-switch";
> > reg = <0x71010000 0x10000>,
> > <0x71030000 0x10000>,
> > ...
>
> I don't understand how your answer relates to "reg=<0 0>;". How is it
> going to become 0x71010000 if there is no other reg/ranges set in parent
> nodes. The node has only one IO address, but you say the switch has 20
> addresses...
>
> Are we talking about same hardware?

Yes. The switch driver for both the VSC7512 and VSC7514 use up to ~20 regmaps
depending on what capabilities it is to have. In the 7514 they are all
memory-mapped from the device tree. While the 7512 does need these
regmaps, they are managed by the MFD, not the device tree. So there
isn't a _need_ for them to be here, since at the end of the day they're
ignored.

The "reg=<0 0>;" was my attempt to indicate that they are ignored, but I
understand that isn't desired. So moving forward I'll add all the
regmaps back into the device tree.

>
> Best regards,
> Krzysztof
>