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

[Jon Hunter <jonathanh@nvidia.com>]

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