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From: Thierry Reding <thierry.reding@gmail.com>
To: Thierry Reding <thierry.reding@gmail.com>,
	Krzysztof Kozlowski <krzk@kernel.org>
Cc: Rob Herring <robh@kernel.org>, Conor Dooley <conor+dt@kernel.org>,
	Jon Hunter <jonathanh@nvidia.com>,
	linux-tegra@vger.kernel.org, devicetree@vger.kernel.org
Subject: [PATCH 1/3] dt-bindings: memory: tegra: Document DBB clock for Tegra264
Date: Wed,  5 Nov 2025 17:05:11 +0100	[thread overview]
Message-ID: <20251105160513.2638408-2-thierry.reding@gmail.com> (raw)
In-Reply-To: <20251105160513.2638408-1-thierry.reding@gmail.com>

From: Thierry Reding <treding@nvidia.com>

Accesses to external memory are routed through the data backbone (DBB)
on Tegra264. A separate clock feeds this path and needs to be enabled
whenever an IP block makes an access to external memory. The external
memory controller driver is the best place to control this clock since
it knows how many devices are actively accessing memory.

Document the presence of this clock on Tegra264 only.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 .../memory-controllers/nvidia,tegra186-mc.yaml        | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra186-mc.yaml b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra186-mc.yaml
index b901f1b3e0fc..f0448d9ea1ba 100644
--- a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra186-mc.yaml
+++ b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra186-mc.yaml
@@ -92,10 +92,12 @@ patternProperties:
       clocks:
         items:
           - description: external memory clock
+          - description: data backbone clock
 
       clock-names:
         items:
           - const: emc
+          - const: dbb
 
       "#interconnect-cells":
         const: 0
@@ -115,6 +117,9 @@ patternProperties:
             reg:
               maxItems: 1
 
+            clocks:
+              maxItems: 1
+
       - if:
           properties:
             compatible:
@@ -124,6 +129,9 @@ patternProperties:
             reg:
               minItems: 2
 
+            clocks:
+              maxItems: 1
+
       - if:
           properties:
             compatible:
@@ -133,6 +141,9 @@ patternProperties:
             reg:
               minItems: 2
 
+            clocks:
+              maxItems: 1
+
       - if:
           properties:
             compatible:
-- 
2.51.2


  reply	other threads:[~2025-11-05 16:05 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-11-05 16:05 [PATCH 0/3] arm64: tegra: Add DBB clock to EMC on Tegra264 Thierry Reding
2025-11-05 16:05 ` Thierry Reding [this message]
2025-11-05 17:31   ` [PATCH 1/3] dt-bindings: memory: tegra: Document DBB clock for Tegra264 Rob Herring (Arm)
2025-11-05 19:49     ` Thierry Reding
2025-11-05 16:05 ` [PATCH 2/3] memory: tegra: Add support for DBB clock on Tegra264 Thierry Reding
2025-11-05 16:05 ` [PATCH 3/3] arm64: tegra: Add DBB clock to EMC " Thierry Reding

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