Hi Rob,
On Fri, Jul 1, 2022 at 6:33 PM Rob Herring <robh@xxxxxxxxxx> wrote:
>
> On Tue, Jun 28, 2022 at 02:44:35PM +0200, Martin Blumenstingl wrote:
> > The Lantiq Amazon-SE, Danube, xRX100 and xRX200 SoCs have up to two USB2
> > PHYs which are part of the RCU register space. The RCU registers on
> > these SoCs are using big endian. Update the binding for these SoCs to
> > properly describe this IP:
> > - Add compatible strings for Amazon-SE, Danube and xRX100
> > - Rename the xRX200 compatible string (which is not used anywhere) and
> > switch to the one previously documented in mips/lantiq/rcu.txt
> > - Allow usage of "simple-mfd" and "syscon" in the compatible string so the
> > child devices (USB2 PHYs) can be described
> > - Allow #address-cells and #size-cells to be set to 1 for describing the
> > child devices (USB2 PHYs)
> > - #reset-cells must always be 3 (offset, reset bit and status bit) on the
> > legacy SoCs while LGM uses a fixed value of 2 (offset and reset bit -
> > status bit is always identical to the reset bit).
> >
> > Signed-off-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
> > ---
> > .../bindings/reset/intel,rcu-gw.yaml | 84 +++++++++++++++++--
> > 1 file changed, 79 insertions(+), 5 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/reset/intel,rcu-gw.yaml b/Documentation/devicetree/bindings/reset/intel,rcu-gw.yaml
> > index be64f8597710..b90913c7b7d3 100644
> > --- a/Documentation/devicetree/bindings/reset/intel,rcu-gw.yaml
> > +++ b/Documentation/devicetree/bindings/reset/intel,rcu-gw.yaml
> > @@ -11,9 +11,16 @@ maintainers:
> >
> > properties:
> > compatible:
> > - enum:
> > - - intel,rcu-lgm
> > - - intel,rcu-xrx200
>
> It is okay to remove/change this because ?
I'll update the description in v2. The "intel,rcu-xrx200" compatible
string isn't used anywhere (upstream or downstream in OpenWrt).
u-boot on Lantiq xRX200 SoCs is too old to pass a dtb to the kernel,
so we're appending the DTB to the kernel image.
> > + oneOf:
> > + - items:
> > + - enum:
> > + - lantiq,ase-rcu
> > + - lantiq,danube-rcu
> > + - lantiq,xrx100-rcu
> > + - lantiq,xrx200-rcu
> > + - const: simple-mfd
>
> This says child nodes have 0 dependence on anything in the parent node.
> Such as a clock in the parent needing to be enabled.
>
> > + - const: syscon
>
> Given the child nodes depend on this, I find the combination to be a
> contradiction. But it's widely used, so oh well.
I can think of two ways to solve this:
1) remove the simple-mfd compatible string and make the driver also
discover child nodes
2) remove the simple-mfd compatible string and remove the USB PHY
child nodes - then add add #phy-cells = <1> to the RCU node itself
(and somehow update the RCU and USB PHY drivers accordingly)
3) introduce a separate child node for the reset-controller, then the
child nodes depend on each other (but there's no strict dependency on
the parent anymore other than the fact that the parent needs a
"syscon" compatible string).
My understanding of this IP block is that it was initially designed as
a reset controller, hence its name "reset controller unit" (RCU). Then
additional logic was added after the fact.
So I think 1) (dropping the simple-mfd compatible string) or 2)
(dropping the simple-mfd compatible string and the child nodes
altogether) is the right way to go here. Which route would you go and
why?
[...]
> > +patternProperties:
> > + "^usb2-phy@[0-9a-f]+$":
> > + type: object
> > + $ref: "../phy/lantiq,xway-rcu-usb2-phy.yaml"
> > +
> > +allOf:
> > + - if:
> > + properties:
> > + compatible:
> > + contains:
> > + const: intel,rcu-lgm
> > + then:
> > + properties:
> > + "#reset-cells":
> > + const: 2
>
> else:
> properties:
> "#reset-cells":
> const: 3
much shorter, thanks - I'll take care of this in v2.
[...]
> > + usb_phy0: usb2-phy@18 {
> > + compatible = "lantiq,xrx200-usb2-phy";
> > + reg = <0x18 4>, <0x38 4>;
> > + status = "disabled";
>
> Why is your example disabled? Don't use 'status' in examples.
I should know this better - I'll fix this in v2.
Best regards,
Martin
