Re: [Patch v3 3/9] dt-bindings: arm: tegra: Add NVIDIA Tegra194 axi2apb binding

Rob Herring
2021-12-27T15:46:50Z

On Thu, Dec 23, 2021 at 4:24 AM Sumit Gupta <sumitg@nvidia.com> wrote:
> > On Tue, Dec 21, 2021 at 06:21:11PM +0530, Sumit Gupta wrote:
> >> Add device-tree binding documentation to represent the axi2apb bridges
> >> used by Control Backbone (CBB) 1.0 in Tegra194 SOC. All errors for APB
> >> slaves are reported as slave error because APB bas single bit to report
> >> error. So, CBB driver needs to further check error status registers of
> >> all the axi2apb bridges to find error type.
> >>
> >> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
> >> Signed-off-by: Thierry Reding <treding@nvidia.com>
> >> ---
> >> .../arm/tegra/nvidia,tegra194-axi2apb.yaml | 40 +++++++++++++++++++
> >> 1 file changed, 40 insertions(+)
> >> create mode 100644 Documentation/devicetree/bindings/arm/tegra/nvidia,tegra194-axi2apb.yaml
> >>
> >> diff --git a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra194-axi2apb.yaml b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra194-axi2apb.yaml
> >> new file mode 100644
> >> index 000000000000..788a13f8aa93
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra194-axi2apb.yaml
> >> @@ -0,0 +1,40 @@
> >> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> >> +%YAML 1.2
> >> +---
> >> +$id: "http://devicetree.org/schemas/arm/tegra/nvidia,tegra194-axi2apb.yaml#"
> >> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> >> +
> >> +title: NVIDIA Tegra194 AXI2APB bridge
> >> +
> >> +maintainers:
> >> + - Sumit Gupta <sumitg@nvidia.com>
> >> +
> >> +properties:
> >> + $nodename:
> >> + pattern: "^axi2apb@([0-9a-f]+)$"
> >> +
> >> + compatible:
> >> + enum:
> >> + - nvidia,tegra194-axi2apb
> >> +
> >> + reg:
> >> + maxItems: 6
> >> + description: Physical base address and length of registers for all bridges
> >> +
> >> +additionalProperties: false
> >> +
> >> +required:
> >> + - compatible
> >> + - reg
> >> +
> >> +examples:
> >> + - |
> >> + axi2apb: axi2apb@2390000 {
> >
> > As axi2apb appears to be a bus, then all the child nodes (APB devices)
> > should be under this node.
>
> axi2apb is a bridge which coverts an AXI to APB interface and not a bus.

A bus and bridge node are pretty much one and the same in DT
representation. A PCI host bridge has a PCI bus beneath it for
example.

Rob