Thread (17 messages) 17 messages, 4 authors, 2024-03-01

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

From: Georgi Djakov <djakov@kernel.org>
Date: 2024-02-29 20:17:30
Also in: linux-arm-msm, linux-devicetree, linux-iommu, lkml

Hi Krzysztof,

On 29.02.24 19:59, Krzysztof Kozlowski wrote:
On 26/02/2024 18:22, Georgi Djakov wrote:
quoted
The "apps_smmu" on the Qualcomm sdm845 platform is an implementation
of the SMMU-500, that consists of a single TCU (Translation Control
Unit) and multiple TBUs (Translation Buffer Units). These TBUs have
hardware debugging features that are specific and only present on
Qualcomm hardware. Represent them as independent DT nodes. List all
the resources that are needed to operate them (such as registers,
clocks, power domains and interconnects).

Signed-off-by: Georgi Djakov <redacted>
---
  .../devicetree/bindings/iommu/qcom,tbu.yaml   | 65 +++++++++++++++++++
  1 file changed, 65 insertions(+)
  create mode 100644 Documentation/devicetree/bindings/iommu/qcom,tbu.yaml
Heh, I wonder how did you solve Robin's comments. I don't see you
responding to Robin. Just v5 sent...
Yeah, i didn't respond because his response was clear to me. He responded
to the fundamental question whether to model the TBUs as child DT nodes of
the SMMU or as standalone nodes. So in the first versions of this patchset
we tried to explore the path with "child" nodes and search if there are any
other implementation than the Qualcomm one and try to find some common
binding... and Robin's objection was exactly to that. It seems that adding
more functionalities in TBUs (which requires resource management) is only
a Qualcomm thing and common binding does not make sense, so now we are
going with standalone DT nodes as he suggested.

Thanks,
Georgi

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