Re: [PATCH v2 11/28] dt-bindings: gpu: panthor: Document AM system bindings

[Krzysztof Kozlowski <krzk@kernel.org>]

On 11/11/2026 11:43, Karunika Choo wrote:
> On 11/11/2026 08:29, Krzysztof Kozlowski wrote:
>> On Tue, Nov 10, 2026 at 03:38:32PM +0000, Karunika Choo wrote:
>>> Mali 5th-Gen AM GPUs expose an AM_SYSTEM block for GPU-wide control and
>>> the AM_ASSIGN block for HW resource assignment outside the GPU
>>> job submission register window.
>>>
>>> Document the system node compatible, register and interrupt resources,
>>> GPU clock, and assignment properties for HW resource assignment.
>>>
>>> Signed-off-by: Karunika Choo <karunika.choo@arm.com>
>>> ---
>>> v2:
>>> - Add an optional AM_ASSIGN register range. Require this range when the
>>>   assignments node is present.
>>> - Describe resource-group assignments for AXI buses, partitions, slices
>>>   and access windows on partition-capable GPUs.
>>> - Allow gpu-arbitration child nodes and the #address-cells, #size-cells
>>>   and ranges properties.
>>> - Remove the panthor-system node-name restriction.
>>> - Remove gpu-supply from the schema and example.
>>> - Add an example with assignments for partition-capable GPU with four
>>>   resource groups.
>>> - Move the MAINTAINERS update to the GPU schema patch.
>>>
>>>  .../bindings/gpu/arm,mali-gen5-am-system.yaml | 196 ++++++++++++++++++
>>>  1 file changed, 196 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/gpu/arm,mali-gen5-am-system.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/gpu/arm,mali-gen5-am-system.yaml b/Documentation/devicetree/bindings/gpu/arm,mali-gen5-am-system.yaml
>>> new file mode 100644
>>> index 0000000000000..9e0477b8b723a
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/gpu/arm,mali-gen5-am-system.yaml
>>> @@ -0,0 +1,196 @@
>>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>>> +# Copyright 2026 ARM Limited. All rights reserved.
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/gpu/arm,mali-gen5-am-system.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: ARM Mali 5th-Gen GPU System Device
>>> +
>>> +maintainers:
>>> +  - Liviu Dudau <liviu.dudau@arm.com>
>>> +  - Boris Brezillon <boris.brezillon@collabora.com>
>>> +
>>> +properties:
>>> +  compatible:
>>> +    items:
>>> +      - const: arm,mali-gen5-am-system
>>> +
>>> +  reg:
>>> +    minItems: 1
>>> +    maxItems: 2
>>
>> Why is this flexible? There is no description in the binding which would
>> explain oddities in choices of hardware representation.
> 
> I will restore the description that was previously asked to be dropped.

Hm, let me open the cover letter to find lore link to previous
discussion and check... ah wait, no cover letter!

> 
>>> +
>>> +  reg-names:
>>> +    minItems: 1
>>> +    items:
>>> +      - const: system
>>> +      - const: assign
>>> +
>>> +  interrupts:
>>> +    maxItems: 1
>>> +
>>> +  clocks:
>>> +    maxItems: 1
>>> +
>>> +  dma-coherent: true
>>> +
>>> +  "#address-cells": true
>>> +
>>> +  "#size-cells": true
>>
>> Both need to be const or enum.
>>
>>> +
>>> +  ranges: true
>>> +
>>> +  assignments:
>>
>> Do not mix nodes with and without bus addressing. That's mess.
> 
> Hi, I was asked to use a more generic DT such that should the

By whom?

> hardware registers change in the future we can still retain
> some compatibility. Is it necessarily a problem?

Bindings are not generic, but specific.

...

>>> +patternProperties:
>>> +  '^gpu-arbitration@[a-f0-9]+$':
>>> +    $ref: arm,mali-gen5-am-arbitration.yaml#
>>
>> There is no such file. You did not really test it.
> 
> Sorry, this was included from a later patch that
> introduces this file. I will move it there in v3.
> 
>>
>>> +
>>> +required:
>>> +  - compatible
>>> +  - reg
>>> +  - reg-names
>>> +  - interrupts
>>> +  - clocks
>>> +
>>> +additionalProperties: false
>>
>> This goes after allOf: block.
>>
>>> +
>>> +allOf:
>>> +  - if:
>>> +      required:
>>> +        - assignments
>>> +    then:
>>> +      properties:
>>> +        reg:
>>> +          minItems: 2
>>> +        reg-names:
>>> +          minItems: 2
>>> +
>>> +examples:
>>> +  - |
>>> +    #include <dt-bindings/interrupt-controller/irq.h>
>>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>>> +
>>> +    gpu-system@68000000 {
>>> +      compatible = "arm,mali-gen5-am-system";
>>> +      reg = <0x68000000 0x10000>;
>>> +      reg-names = "system";
>>> +      interrupts = <GIC_SPI 168 IRQ_TYPE_LEVEL_HIGH>;
>>> +      clocks = <&mali_gpu_clk>;
>>> +    };
>>> +  - |
>>> +    #include <dt-bindings/interrupt-controller/irq.h>
>>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>>> +
>>> +    gpu-system@68000000 {
>>> +      compatible = "arm,mali-gen5-am-system";
>>> +      reg = <0x68000000 0x10000>, <0x68010000 0x10000>;
>>> +      reg-names = "system", "assign";
>>> +      interrupts = <GIC_SPI 168 IRQ_TYPE_LEVEL_HIGH>;
>>> +      clocks = <&mali_gpu_clk>;
>>> +
>>> +      assignments {
>>> +        #address-cells = <1>;
>>> +        #size-cells = <0>;
>>> +
>>> +        resource-group@0 {
>>> +          reg = <0>;
>>> +          arm,axi-bus = <0>;
>>> +          arm,partition-mask = <0x1>;
>>> +          arm,slice-mask = <0x3>;
>>> +          arm,access-window-mask = <0xf>;
>>> +        };
>>> +
>>> +        resource-group@1 {
>>> +          reg = <1>;
>>> +          arm,axi-bus = <0>;
>>> +          arm,partition-mask = <0x2>;
>>> +          arm,slice-mask = <0xc>;
>>> +          arm,access-window-mask = <0xf0>;
>>> +        };
>>> +
>>> +        resource-group@2 {
>>> +          reg = <2>;
>>> +          arm,axi-bus = <1>;
>>> +          arm,partition-mask = <0x4>;
>>> +          arm,slice-mask = <0x30>;
>>> +          arm,access-window-mask = <0xf00>;
>>> +        };
>>> +
>>> +        resource-group@3 {
>>> +          reg = <3>;
>>> +          arm,axi-bus = <1>;
>>> +          arm,partition-mask = <0x8>;
>>> +          arm,slice-mask = <0xc0>;
>>> +          arm,access-window-mask = <0xf000>;
>>> +        };
>>
>> Your example is incomplete.
> 
> Could you clarify what specifically is missing?

ll the properties you added in the binding.

Best regards,
Krzysztof