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

Frank Li
2026-03-02T20:31:15Z

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@nvidia.com>
> ---
> .../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@nvidia.com>
> - Akhil R <akhilrajeev@nvidia.com>
>
> -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.

Frank

> + then:
> + required:
> + - resets
> + - reset-names
> +
> additionalProperties: false
>
> examples:
> --
> 2.50.1
>