Re: [PATCH V3 1/2] dt-bindings: PCI: tegra234: Add ECAM support

[Jon Hunter <jonathanh@nvidia.com>]

On 15/11/2022 02:01, Rob Herring wrote:
> On Mon, Nov 14, 2022 at 03:53:32PM +0000, Jon Hunter wrote:
>> From: Vidya Sagar <vidyas@nvidia.com>
>>
>> Add support for ECAM aperture that is only supported for Tegra234
>> devices.
>>
>> Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
>> Co-developed-by: Jon Hunter <jonathanh@nvidia.com>
>> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
>> ---
>> Changes since V2:
>> - Avoid duplication of reg items and reg-names
>> Changes since V1:
>> - Restricted the ECAM aperture to only Tegra234 devices that support it.
>>
>>   .../bindings/pci/nvidia,tegra194-pcie.yaml    | 34 +++++++++++++++++--
>>   .../devicetree/bindings/pci/snps,dw-pcie.yaml |  2 +-
>>   2 files changed, 33 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/pci/nvidia,tegra194-pcie.yaml b/Documentation/devicetree/bindings/pci/nvidia,tegra194-pcie.yaml
>> index 75da3e8eecb9..fe81d52c7277 100644
>> --- a/Documentation/devicetree/bindings/pci/nvidia,tegra194-pcie.yaml
>> +++ b/Documentation/devicetree/bindings/pci/nvidia,tegra194-pcie.yaml
>> @@ -27,6 +27,7 @@ properties:
>>         - nvidia,tegra234-pcie
>>   
>>     reg:
>> +    minItems: 4
>>       items:
>>         - description: controller's application logic registers
>>         - description: configuration registers
>> @@ -35,13 +36,16 @@ properties:
>>             available for software access.
>>         - description: aperture where the Root Port's own configuration
>>             registers are available.
>> +      - description: aperture to access the configuration space through ECAM.
>>   
>>     reg-names:
>> +    minItems: 4
>>       items:
>>         - const: appl
>>         - const: config
>>         - const: atu_dma
>>         - const: dbi
>> +      - const: ecam
> 
> Wouldn't this be mutually exclusive with 'config'? 'config' is not
> really h/w, but an just an iATU window typically.

Yes that is true, however, I was chatting with Sagar and we really need 
both ranges to be defined.

> Where's the driver change to use this?

For Linux there is not one. However, we need this for our port of the 
EDK2 bootloader [0] that parses device-tree and can support booting 
Linux with either device-tree or ACPI. We wanted to have a common 
device-tree we can use for EDK2 and Linux.

Jon

[0] https://github.com/NVIDIA/edk2-nvidia/wiki

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