Re: [PATCH v2 2/9] dt-bindings: dma: nvidia,tegra186-gpc-dma: Make reset optional

[Jon Hunter]

On 02/03/2026 20:31, Frank Li wrote:
> On Mon, Mar 02, 2026 at 06:02:32PM +0530, Akhil R wrote:
> > In Tegra264, GPCDMA reset control is not exposed to Linux and is handled
> > by the boot firmware.
> >
> > Although reset was not exposed in Tegra234 as well, the firmware supported
> > a dummy reset which just returns success on reset without doing an actual
> > reset. This is also not supported in Tegra264 BPMP. Therefore mark 'reset'
> > and 'reset-names' properties as required only for devices prior to
> > Tegra264.
> >
> > This also necessitates that the Tegra264 compatible to be standalone and
> > cannot have the fallback compatible of Tegra186. Since there is no
> > functional impact, we keep reset as required for Tegra234 to avoid
> > breaking the ABI.
> >
> > Signed-off-by: Akhil R <akhilrajeev@xxxxxxxxxx>
> > ---
> >   .../bindings/dma/nvidia,tegra186-gpc-dma.yaml | 22 ++++++++++++++-----
> >   1 file changed, 16 insertions(+), 6 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml b/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml
> > index 1e7b5ddd4658..34c9b41aecfc 100644
> > --- a/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml
> > +++ b/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml
> > @@ -16,16 +16,13 @@ maintainers:
> >     - Rajesh Gumasta <rgumasta@xxxxxxxxxx>
> >     - Akhil R <akhilrajeev@xxxxxxxxxx>
> >
> > -allOf:
> > -  - $ref: dma-controller.yaml#
> > -
> >   properties:
> >     compatible:
> >       oneOf:
> > +      - const: nvidia,tegra264-gpcdma
> >         - const: nvidia,tegra186-gpcdma
>
> use enum
>
>           - enum:
>               - nvidia,tegra186-gpcdma
>               - nvidia,tegra264-gpcdma
>
> >         - items:
> >             - enum:
> > -              - nvidia,tegra264-gpcdma
> >                 - nvidia,tegra234-gpcdma
> >                 - nvidia,tegra194-gpcdma
> >             - const: nvidia,tegra186-gpcdma
> > @@ -65,12 +62,25 @@ required:
> >     - compatible
> >     - reg
> >     - interrupts
> > -  - resets
> > -  - reset-names
> >     - "#dma-cells"
> >     - iommus
> >     - dma-channel-mask
> >
> > +allOf:
> > +  - $ref: dma-controller.yaml#
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            enum:
> > +              - nvidia,tegra186-gpcdma
> > +              - nvidia,tegra194-gpcdma
> > +              - nvidia,tegra234-gpcdma
>
> nvidia,tegra234-gpcdma must have fallback nvidia,tegra186-gpcdma, so
> needn't nvidia,tegra234-gpcdma here.

I guess the same is true for tegra194 as well.

Jon

--
nvpublic