Re: [RFC PATCH 1/2] dt-bindings: pcie: Document QCOM PCIE ECAM compatible root complex

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On 4/8/2024 11:21 PM, Krzysztof Kozlowski wrote:
On 08/04/2024 21:09, Mayank Rana wrote:
+  Firmware configures PCIe controller in RC mode with static iATU window mappings
+  of configuration space for entire supported bus range in ECAM compatible mode.
+
+maintainers:
+  - Mayank Rana <quic_mrana@xxxxxxxxxxx>
+
+allOf:
+  - $ref: /schemas/pci/pci-bus.yaml#
+  - $ref: /schemas/power-domain/power-domain-consumer.yaml
+
+properties:
+  compatible:
+    const: qcom,pcie-ecam-rc

No, this must have SoC specific compatibles.
This driver is proposed to work with any PCIe controller supported ECAM
functionality on Qualcomm platform
where firmware running on other VM/processor is controlling PCIe PHY and
controller for PCIe link up functionality.
Do you still suggest to have SoC specific compatibles here ?

What does the writing-bindings document say? Why this is different than
all other bindings?
Thank you for all your review comment and suggestions.

If it is must to have SOC name, then I am not sure how pci-host-generic.c driver having non SOC prefix for standard ECAM driver. I am here saying this is QCOM vendor specific generic ECAM driver. saying that it seems that I would be updating now pci-host-generic.c driver to add generic functionality as Rob suggested part of review comment. With that I am seeing possible options as i.e. continue using default generic compatible as "pcie-host-ecam-generic" OR use new as "qcom,pcie-host-ecam-generic". will this work ?>>>> +
+  reg:
+    minItems: 1

maxItems instead

+    description: ECAM address space starting from root port till supported bus range
+
+  interrupts:
+    minItems: 1
+    maxItems: 8

This is way too unspecific.
will review and update.
+
+  ranges:
+    minItems: 2
+    maxItems: 3

Why variable?
It depends on how ECAM configured to support 32-bit and 64-bit based
prefetch address space.
So there are different combination of prefetch (32-bit or 64-bit or
both) and non-prefetch (32-bit), and IO address space available. hence
kept it as variable with based on required use case and address space
availability.

Really? So same device has it configured once for 32 once for 64-bit
address space? Randomly?
no. as binding is not saying for any specific SOC. Depends on memory map
on particular SOC, how PCIe address space available based on that this would change for particular SOC variant.
Best regards,
Krzysztof





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