Re: [PATCH] dt-bindings: host1x: Add missing 'dma-coherent'

[Jon Hunter <jonathanh@nvidia.com>]

On 10/04/2024 07:18, Krzysztof Kozlowski wrote:
> On 09/04/2024 10:23, Jon Hunter wrote:
>> The dtbs_check reports that the 'dma-coherent' property is "unevaluated
>> and invalid" for the host1x@13e00000 device on Tegra194 and Tegra234
>> platforms. Fix this by updating the dt-binding document for host1x to
>> add the 'dma-coherent' property for these devices.
> 
> That's not really proper reason. What if DTS is wrong? The reason could
> be if device is actually DMA coherent...

In this case the DTS is correct. I guess I should have been more 
explicit about that.

>> Fixes: 361238cdc525 ("arm64: tegra: Mark host1x as dma-coherent on Tegra194/234")
>> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
>> ---
>>   .../bindings/display/tegra/nvidia,tegra20-host1x.yaml | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/display/tegra/nvidia,tegra20-host1x.yaml b/Documentation/devicetree/bindings/display/tegra/nvidia,tegra20-host1x.yaml
>> index 94c5242c03b2..3563378a01af 100644
>> --- a/Documentation/devicetree/bindings/display/tegra/nvidia,tegra20-host1x.yaml
>> +++ b/Documentation/devicetree/bindings/display/tegra/nvidia,tegra20-host1x.yaml
>> @@ -177,6 +177,15 @@ allOf:
>>   
>>         required:
>>           - reg-names
>> +  - if:
>> +      properties:
>> +        compatible:
>> +          contains:
>> +            enum:
>> +              - nvidia,tegra194-host1x
>> +    then:
>> +      properties:
>> +        dma-coherent: true
> 
> Do not define properties in allOf. Put it in top-level. If not all
> devices are DMA coherent, you can disallow it for certain variants (:false).


So for host1x we currently have the following devices supported ...

properties:
   compatible:
     oneOf:
       - enum:
           - nvidia,tegra20-host1x
           - nvidia,tegra30-host1x
           - nvidia,tegra114-host1x
           - nvidia,tegra124-host1x
           - nvidia,tegra210-host1x
           - nvidia,tegra186-host1x
           - nvidia,tegra194-host1x
           - nvidia,tegra234-host1x

       - items:
           - const: nvidia,tegra132-host1x
           - const: nvidia,tegra124-host1x


Now only the Tegra194 and Tegra234 are coherent (which are the latest 
devices). So rather than add this to the top and then filter out all 
those that are not supported, I opted for the above because there is 
only 2 devices that need this. Admittedly, as much as I like the yaml 
bindings, for things like this, it is not really clear which is the best 
way to handle, so appreciate the guidance.

Jon

-- 
nvpublic