linux-kernel - [PATCH v4] dt-bindings: opp: operating-points-v2-ti-cpu: Describe opp-supported-hw

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Message-ID: <20240918053317.1390626-1-d-gole@ti.com>
Date: Wed, 18 Sep 2024 11:03:17 +0530
From: Dhruva Gole <d-gole@...com>
To: Viresh Kumar <vireshk@...nel.org>, Stephen Boyd <sboyd@...nel.org>,
        Rob
 Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor
 Dooley <conor+dt@...nel.org>
CC: <linux-pm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Dhruva Gole <d-gole@...com>,
        <nm@...com>, <vigneshr@...com>
Subject: [PATCH v4] dt-bindings: opp: operating-points-v2-ti-cpu: Describe opp-supported-hw

It seems like we missed migrating the complete information from the old
DT binding where we had described what the opp-supported-hw is supposed
to describe. Hence, bring back the description from the previous binding
to the current one along with a bit more context on what the values are
supposed to be.

Fixes: e576a9a8603f ("dt-bindings: cpufreq: Convert ti-cpufreq to json schema")
Signed-off-by: Dhruva Gole <d-gole@...com>
---

Changes in v4:
- Fix dt_binding_check errors on previous revision.
- As per Rob's suggestion, used a blank line in between description
  and the paragraph.
- Reworded the description a bit.
- Link to v3: https://lore.kernel.org/all/20240917095252.1292321-1-d-gole@ti.com/

Changes in v3:
- Use the items: and then provide description for both required items.
  This tries to address Rob's comments on previous revision.
- I've not use min/max Items as the 2 descriptions items implicitly
  imply that number of bitfields needed are 2.
- Link to v2: https://lore.kernel.org/all/20240905-b4-opp-dt-binding-fix-v2-1-1e3d2a06748d@ti.com/

Changes in v2:
- Drop the patch where I updated Maintainers since it's already picked
  by Viresh.
- Add more details of how to populate the property based on device
  documents like TRM/ datasheet.
- Link to v1: https://lore.kernel.org/r/20240903-b4-opp-dt-binding-fix-v1-0-f7e186456d9f@ti.com

---
 .../opp/operating-points-v2-ti-cpu.yaml       | 20 ++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/opp/operating-points-v2-ti-cpu.yaml b/Documentation/devicetree/bindings/opp/operating-points-v2-ti-cpu.yaml
index fd0c8d5c5f3e..7c07410638db 100644
--- a/Documentation/devicetree/bindings/opp/operating-points-v2-ti-cpu.yaml
+++ b/Documentation/devicetree/bindings/opp/operating-points-v2-ti-cpu.yaml
@@ -45,7 +45,25 @@ patternProperties:
       clock-latency-ns: true
       opp-hz: true
       opp-microvolt: true
-      opp-supported-hw: true
+      opp-supported-hw:
+        items:
+          items:
+            - description:
+
+                The revision of the SoC the OPP is supported by.
+                This can be easily obtained from the datasheet of the
+                part being ordered/used. For eg. it will be 0x01 for SR1.0
+            - description:
+
+                The eFuse bits that indicate the particular OPP is available.
+                The device datasheet has a table talking about Device Speed Grades.
+                This table is to be sorted with only the unique elements of the
+                MAXIMUM OPERATING FREQUENCY starting from the first row
+                which tells the lowest OPP, to the highest. The corresponding bits
+                need to be set based on N elements of speed grade the device supports.
+                So, if there are 3 possible unique MAXIMUM OPERATING FREQUENCY
+                in the table, then BIT(0) | (1) | (2) will be set, which means
+                the value shall be 0x7.
       opp-suspend: true
       turbo-mode: true
 
-- 
2.34.1