linux-kernel - Re: [PATCH V3 RESEND 1/2] dt-bindings: spi: tegra: Document IOMMU property for Tegra234 QSPI

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Message-ID: <904d3e89-a540-4edd-b748-15e13c431c17@nvidia.com>
Date: Tue, 13 May 2025 11:19:05 +0100
From: Jon Hunter <jonathanh@...dia.com>
To: Conor Dooley <conor@...nel.org>, Vishwaroop A <va@...dia.com>
Cc: krzk@...nel.org, broonie@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
 conor+dt@...nel.org, thierry.reding@...il.com, skomatineni@...dia.com,
 ldewangan@...dia.com, kyarlagadda@...dia.com, smangipudi@...dia.com,
 bgriffis@...dia.com, linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
 linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 RESEND 1/2] dt-bindings: spi: tegra: Document IOMMU
 property for Tegra234 QSPI


On 12/05/2025 17:49, Conor Dooley wrote:
> On Fri, May 09, 2025 at 04:54:08PM +0000, Vishwaroop A wrote:
>> Add the 'iommus' property to the Tegra QSPI device tree binding.
>> The property is needed for Tegra234 when using the internal DMA
>> controller, and is not supported on other Tegra chips, as DMA is
>> handled by an external controller.
>>
>> Signed-off-by: Vishwaroop A <va@...dia.com>
>> ---
>>   .../bindings/spi/nvidia,tegra210-quad.yaml    | 19 ++++++++++++++++---
>>   1 file changed, 16 insertions(+), 3 deletions(-)
>>
>> Changes since v2:
>> - Fixed version number to match the actual version
>> - Added proper changelog section
>> - No functional changes from v2
>>
>> Changes since v1:
>> - Fixed subject prefix to match subsystem (dt-bindings: spi: tegra)
>> - Improved commit message formatting to follow Linux coding style
>> - Clarified that IOMMU is only required for Tegra234 platform
>> - Added explicit disallow for IOMMU on other platforms
>> - Removed redundant explanations of what the patch does
>> - Fixed commit message to use imperative mood
>>
>> Initial Version:
>> - Initial implementation of IOMMU property documentation
>> - Added iommus property to device tree binding
>> - Added support for Tegra234 platform
>> - Added explanation of DMA and IOMMU requirements
>>
>> diff --git a/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml b/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
>> index 48e97e240265..04d3b1a47392 100644
>> --- a/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
>> +++ b/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
>> @@ -10,9 +10,6 @@ maintainers:
>>     - Thierry Reding <thierry.reding@...il.com>
>>     - Jonathan Hunter <jonathanh@...dia.com>
>>   
>> -allOf:
>> -  - $ref: spi-controller.yaml#
>> -
>>   properties:
>>     compatible:
>>       enum:
>> @@ -47,6 +44,9 @@ properties:
>>         - const: rx
>>         - const: tx
>>   
>> +  iommus:
>> +    maxItems: 1
>> +
>>   patternProperties:
>>     "@[0-9a-f]+$":
>>       type: object
>> @@ -69,6 +69,19 @@ required:
>>   
>>   unevaluatedProperties: false
>>   
>> +allOf:
>> +  - $ref: spi-controller.yaml#
>> +  - if:
>> +      properties:
>> +        compatible:
>> +          const: nvidia,tegra234-qspi
> 
>> +    then:
>> +      properties:
>> +        iommus: true
> 
> This is a NOP, no?
> Just invert the case above and drop a clause.


Yes that's true. So just to confirm, your preference is this ...

diff --git 
a/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml 
b/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
index 04d3b1a47392..c45511e9a9ed 100644
--- a/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
+++ b/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad.yaml
@@ -74,11 +74,13 @@ allOf:
    - if:
        properties:
          compatible:
-          const: nvidia,tegra234-qspi
+          contains:
+            enum:
+              - nvidia,tegra210-qspi
+              - nvidia,tegra186-qspi
+              - nvidia,tegra194-qspi
+              - nvidia,tegra241-qspi
      then:
-      properties:
-        iommus: true
-    else:
        properties:
          iommus: false

Thanks!
Jon

-- 
nvpublic