Re: [PATCH v3 1/3] dt-bindings: net: Add T-HEAD dwmac support

From: Drew Fustini
Date: Wed Oct 02 2024 - 15:08:17 EST


On Tue, Oct 01, 2024 at 08:58:34AM +0200, Krzysztof Kozlowski wrote:
> On Mon, Sep 30, 2024 at 11:23:24PM -0700, Drew Fustini wrote:
> > From: Jisheng Zhang <jszhang@xxxxxxxxxx>
> >
> > Add documentation to describe the DesginWare-based GMAC controllers in
> > the T-HEAD TH1520 SoC.
> >
> > Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxx>
> > Signed-off-by: Emil Renner Berthing <emil.renner.berthing@xxxxxxxxxxxxx>
> > [drew: rename compatible, add apb registers as second reg of gmac node]
> > Signed-off-by: Drew Fustini <dfustini@xxxxxxxxxxxxxxx>
> > ---
> > .../devicetree/bindings/net/snps,dwmac.yaml | 1 +
> > .../devicetree/bindings/net/thead,th1520-gmac.yaml | 97 ++++++++++++++++++++++
> > MAINTAINERS | 1 +
> > 3 files changed, 99 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/net/snps,dwmac.yaml b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> > index 4e2ba1bf788c..474ade185033 100644
> > --- a/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> > +++ b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> > @@ -99,6 +99,7 @@ properties:
> > - snps,dwxgmac-2.10
> > - starfive,jh7100-dwmac
> > - starfive,jh7110-dwmac
> > + - thead,th1520-gmac
> >
> > reg:
> > minItems: 1
> > diff --git a/Documentation/devicetree/bindings/net/thead,th1520-gmac.yaml b/Documentation/devicetree/bindings/net/thead,th1520-gmac.yaml
> > new file mode 100644
> > index 000000000000..fef1810b10c4
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/net/thead,th1520-gmac.yaml
> > @@ -0,0 +1,97 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/net/thead,th1520-gmac.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: T-HEAD TH1520 GMAC Ethernet controller
> > +
> > +maintainers:
> > + - Drew Fustini <dfustini@xxxxxxxxxxxxxxx>
> > +
> > +description: |
> > + The TH1520 GMAC is described in the TH1520 Peripheral Interface User Manual
> > + https://git.beagleboard.org/beaglev-ahead/beaglev-ahead/-/tree/main/docs
> > +
> > + Features include
> > + - Compliant with IEEE802.3 Specification
> > + - IEEE 1588-2008 standard for precision networked clock synchronization
> > + - Supports 10/100/1000Mbps data transfer rate
> > + - Supports RGMII/MII interface
> > + - Preamble and start of frame data (SFD) insertion in Transmit path
> > + - Preamble and SFD deletion in the Receive path
> > + - Automatic CRC and pad generation options for receive frames
> > + - MDIO master interface for PHY device configuration and management
> > +
> > + The GMAC Registers consists of two parts
> > + - APB registers are used to configure clock frequency/clock enable/clock
> > + direction/PHY interface type.
> > + - AHB registers are use to configure GMAC core (DesignWare Core part).
> > + GMAC core register consists of DMA registers and GMAC registers.
> > +
> > +select:
> > + properties:
> > + compatible:
> > + contains:
> > + enum:
> > + - thead,th1520-gmac
> > + required:
> > + - compatible
> > +
> > +allOf:
> > + - $ref: snps,dwmac.yaml#
> > +
> > +properties:
> > + compatible:
> > + items:
> > + - enum:
> > + - thead,th1520-gmac
> > + - const: snps,dwmac-3.70a
> > +
> > + reg:
> > + items:
> > + - description: DesignWare GMAC IP core registers
> > + - description: GMAC APB registers
> > +
> > + reg-names:
> > + items:
> > + - const: dwmac
> > + - const: apb
>
> I don't get why none of snps,dwmac properties are restricted. How many
> interrupts do you have here? How many clocks? resets?

Thanks for pointing this out. Yes, I forgot to document the clocks,
interrupts and resets.

There needs to be 2 clocks (stmmaceth and pclk). There also needs to be
2 resets: each GMAC has a reset plus a seperate reset for the GMAC AXI
interface. There is 1 interrupt (macirq) but it is optional. The BeagleV
Ahead uses it but the LicheePi 4A does not use the interrupt.

However, I'm uncertain about how to restrict the snps,dwmac properties.

I see that starfive,jh7110-dwmac.yaml has the following logic. Should I
be adding something like this to restrict the snps,dwmac properties?

---------------------------------------------------------------------
allOf:
- $ref: snps,dwmac.yaml#

- if:
properties:
compatible:
contains:
const: starfive,jh7100-dwmac
then:
properties:
interrupts:
minItems: 2
maxItems: 2

interrupt-names:
minItems: 2
maxItems: 2

resets:
maxItems: 1

reset-names:
const: ahb
<snip>
---------------------------------------------------------------------
>
> > +
> > +required:
> > + - compatible
> > + - reg
> > + - clocks
> > + - clock-names
> > + - interrupts
>
> Drop

Will do.

>
> > + - interrupt-names
>
> Drop

Will do.

>
> > + - phy-mode
> > +
> > +unevaluatedProperties: false
>
> Best regards,
> Krzysztof

Thanks for your review,
Drew