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

Jon Hunter
2026-03-03T13:27:11Z

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@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.

I guess the same is true for tegra194 as well.

Jon

--
nvpublic