Re: [PATCH v5 1/7] dt-bindings: iommu: Add Qualcomm TBU bindings

On Thu, Feb 29, 2024 at 10:09:34PM +0200, Georgi Djakov wrote:

Hi Krzysztof,

On 29.02.24 19:53, Krzysztof Kozlowski wrote:

quoted

On 26/02/2024 18:22, Georgi Djakov wrote:

quoted

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iommu/qcom,tbu.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm TBU (Translation Buffer Unit)
+
+maintainers:
+  - Georgi Djakov [off-list ref]
+
+description:
+  The Qualcomm SMMU500 implementation consists of TCU and TBU. The TBU contains
+  a Translation Lookaside Buffer (TLB) that caches page tables. TBUs provides
+  debug features to trace and trigger debug transactions. There are multiple TBU
+  instances with each client core.
+
+properties:
+  compatible:
+    const: qcom,qsmmuv500-tbu

Why we don't have SoC specific compatibles? If that's for SDM845, then
it should be qcom,sdm845-tbu or qcom,sdm845-qsmmuv500-tbu

Because they should be all compatible (as registers). Adding a SoC compatible
might get overly-specific, but i can also see the benefits in that, so ok will
do it!

Hi Krzysztof,

JFYI that the TBUs are used on our mobile SoCs going up until the SoC
we commercialized in early 2022, Snapdragon 8 Gen 1. Including SDM845
there are three more premium tier SoCs using TBUs plus all of their
value-tier derivatives.  There will also be prior generation premium
tier SoCs along with their derivatives that use the TBU as well. Does
it make sense to have a target-specific compatible string given this? 

Thanks,

Chris.


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