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

[Chris Goldsworthy]

On Thu, Feb 29, 2024 at 10:09:34PM +0200, Georgi Djakov wrote:
> Hi Krzysztof,
> 
> On 29.02.24 19:53, Krzysztof Kozlowski wrote:
> >On 26/02/2024 18:22, Georgi Djakov wrote:
> >>+# 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 <quic_c_gdjako@xxxxxxxxxxx>
> >>+
> >>+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.