linux-kernel - [PATCH v4 3/5] dt-bindings: media: Add the Raspberry Pi HEVC decoder

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Message-Id: <20250701-media-rpi-hevc-dec-v4-3-057cfa541177@raspberrypi.com>
Date: Tue, 01 Jul 2025 17:01:38 +0100
From: Dave Stevenson <dave.stevenson@...pberrypi.com>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>, 
 Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Florian Fainelli <florian.fainelli@...adcom.com>, 
 Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, 
 John Cox <john.cox@...pberrypi.com>, Dom Cobley <dom@...pberrypi.com>, 
 review list <kernel-list@...pberrypi.com>, 
 Ezequiel Garcia <ezequiel@...guardiasur.com.ar>
Cc: John Cox <jc@...esim.co.uk>, Stefan Wahren <wahrenst@....net>, 
 linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org, 
 linux-arm-kernel@...ts.infradead.org, 
 Dave Stevenson <dave.stevenson@...pberrypi.com>
Subject: [PATCH v4 3/5] dt-bindings: media: Add the Raspberry Pi HEVC
 decoder

Adds a binding for the HEVC decoder IP owned by Raspberry Pi.

Instantiations of the decoder IP can currently be found in
the Broadcom BCM2711 and BCM2712 SoCs.

Signed-off-by: Dave Stevenson <dave.stevenson@...pberrypi.com>

---

Updated based on the thread in v3 [1] with Krzystof to drop to only SoC
specific compatible strings.

This still feels wrong to me as this is NOT Broadcom IP - it is solely
owned by Raspberry Pi.

It is the same situation as for the Raspberry Pi ISP Backend where
it was proposed to have
  compatible = "brcm,pispbe-bcm2712", "raspberrypi,pispbe";
in [2]. That proposal was viewed as acceptable by both Rob[3] and Conor[4],
and the binding given a Reviewed-by by Rob[5].

Yes it is found as a block inside an SoC, but the same could be said
for a Synopsys I2C controller ("snps,designware-i2c"), Cadence ethernet
MAC ("cdns,macb"), ARM CPU (eg "arm,cortex-a53"), or any number of other
examples. They are all 3rd party IP blocks found in SoCs, have an SoC specific
compatible defined, but acknowledge the IP owner and use a common fallback
compatible where possible.

Please could we have confirmation that this really is what is required
by device tree?

Thanks
  Dave

[1] https://lore.kernel.org/linux-media/20250423-media-rpi-hevc-dec-v3-3-8fd3fad1d6fb@raspberrypi.com/
[2] https://lore.kernel.org/linux-media/20240213104405.GB5012@pendragon.ideasonboard.com/
[3] https://lore.kernel.org/linux-media/20240215140058.GA4147262-robh@kernel.org/
[4] https://lore.kernel.org/linux-media/20240213-landlady-backstab-6e7da824c99a@spud/
[5] https://lore.kernel.org/linux-media/170932821578.3062059.18150159256247255021.robh@kernel.org/
---
 .../bindings/media/raspberrypi,hevc-dec.yaml       | 72 ++++++++++++++++++++++
 1 file changed, 72 insertions(+)

diff --git a/Documentation/devicetree/bindings/media/raspberrypi,hevc-dec.yaml b/Documentation/devicetree/bindings/media/raspberrypi,hevc-dec.yaml
new file mode 100644
index 000000000000..fe3361bddd1f
--- /dev/null
+++ b/Documentation/devicetree/bindings/media/raspberrypi,hevc-dec.yaml
@@ -0,0 +1,72 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/media/raspberrypi,hevc-dec.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Raspberry Pi HEVC Decoder
+
+maintainers:
+  - John Cox <john.cox@...pberrypi.com>
+  - Dom Cobley <dom@...pberrypi.com>
+  - Dave Stevenson <dave.stevenson@...pberrypi.com>
+
+description:
+  The Raspberry Pi HEVC decoder is a hardware video decode accelerator IP block
+  developed and owned by Raspberry Pi.
+
+  Currently it can be found in the Broadcom BCM2711 and BCM2712 processors used
+  on Raspberry Pi 4 and 5 boards respectively.
+
+properties:
+  compatible:
+    oneOf:
+      - const: brcm,bcm2711-hevc-dec
+      - items:
+          - enum:
+              - brcm,bcm2712-hevc-dec
+          - const: brcm,bcm2711-hevc-dec
+
+  reg:
+    items:
+      - description: The HEVC main register region
+      - description: The Interrupt control register region
+
+  reg-names:
+    items:
+      - const: hevc
+      - const: intc
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: The HEVC block clock
+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - interrupts
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    video-codec@...10000 {
+        compatible = "brcm,bcm2711-hevc-dec";
+        reg = <0x7eb00000 0x10000>, /* HEVC */
+              <0x7eb10000 0x1000>;  /* INTC */
+        reg-names = "hevc",
+                    "intc";
+
+        interrupts = <GIC_SPI 98 IRQ_TYPE_LEVEL_HIGH>;
+
+        clocks = <&clk 0>;
+    };
+
+...

-- 
2.34.1