Re: [PATCH 03/21] dt-bindings: gpu: img: Power domain details

Matt Coster
2024-11-06T11:31:13Z

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On 05/11/2024 18:13, Conor Dooley wrote:
> On Tue, Nov 05, 2024 at 06:05:54PM +0000, Conor Dooley wrote:
>> On Tue, Nov 05, 2024 at 03:58:09PM +0000, Matt Coster wrote:
>>> The single existing GPU (AXE-1-16M) only requires a single power domain.
>>> Subsequent patches will add support for BXS-4-64 MC1, which has two power
>>> domains. Add infrastructure now to allow for this.
>>>
>>> Signed-off-by: Matt Coster <matt.coster@imgtec.com>
>>> ---
>>> .../devicetree/bindings/gpu/img,powervr-rogue.yaml | 29 +++++++++++++++++++++-
>>> 1 file changed, 28 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/gpu/img,powervr-rogue.yaml b/Documentation/devicetree/bindings/gpu/img,powervr-rogue.yaml
>>> index 6924831d3e9dd9b2b052ca8f9d7228ff25526532..55f422be1bc5b7564e3e81f24c4b93857f3e12fe 100644
>>> --- a/Documentation/devicetree/bindings/gpu/img,powervr-rogue.yaml
>>> +++ b/Documentation/devicetree/bindings/gpu/img,powervr-rogue.yaml
>>> @@ -49,7 +49,16 @@ properties:
>>> maxItems: 1
>>>
>>> power-domains:
>>> - maxItems: 1
>>> + minItems: 1
>>> + maxItems: 2
>>> +
>>> + power-domain-names:
>>> + oneOf:
>>> + - items:
>>> + - const: a
>>> + - items:
>>> + - const: a
>>> + - const: b
>
> Additionally, a & b? Are those actually the names for the power domains?

Sadly yes, Rogue has power domains that are literally just A, B, etc. I
wouldn't believe me either; the attached image is taken directly from
the documentation for BXS-4-64.

>>>
>>> required:
>>> - compatible
>>> @@ -57,10 +66,27 @@ required:
>>> - clocks
>>> - clock-names
>>> - interrupts
>>> + - power-domains
>>> + - power-domain-names
>>
>> A new required property is an ABI break. Please explain why this is
>> acceptable in your commit message.

Strictly it's only necessary for multi-domain GPUs, or perhaps in
instances where the SoC power controller already enforces the
dependencies between power domains. In reality, I think it was simply an
oversight not to enfore this requirement in the first place. We have
very, very few cores that require <2 power domains so names are always
required if domains are enumerated in dt.

Would you prefer we drop the requirement for "power-domains" and gate
the requirement for "power-domain-names" behind >2 domains, or just
explain the change properly and make the ABI break now while only one
core is supported?

Cheers,
Matt

>>> additionalProperties: false
>>>
>>> allOf:
>>> + # Cores with a single power domain
>>> + - if:
>>> + properties:
>>> + compatible:
>>> + contains:
>>> + anyOf:
>>> + - const: img,img-axe-1-16m
>>> + then:
>>> + properties:
>>> + power-domains:
>>> + minItems: 1
>>> + maxItems: 1
>>> + power-domain-names:
>>> + items:
>>> + - const: a
>>> # Vendor integrations using a single clock domain
>>> - if:
>>> properties:
>>> @@ -90,4 +116,5 @@ examples:
>>> clock-names = "core";
>>> interrupts = <GIC_SPI 86 IRQ_TYPE_LEVEL_HIGH>;
>>> power-domains = <&k3_pds 187 TI_SCI_PD_EXCLUSIVE>;
>>> + power-domain-names = "a";
>>> };
>>>
>>> --
>>> 2.47.0
>>>

--
Matt Coster
E: matt.coster@imgtec.com

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