Re: [PATCH v4 12/18] dt-bindings: gpu: Add support for T-HEAD TH1520 GPU

[Michal Wilczynski <m.wilczynski@samsung.com>]

On 1/31/25 16:39, Matt Coster wrote:
> On 28/01/2025 19:48, Michal Wilczynski wrote:
>> Add bindings for the PowerVR BXM-4-64 GPU integrated in the T-HEAD
>> TH1520 SoC.  This GPU requires two clocks.
> 
> None of the IMG Rogue GPUs use two clocks; they're all either one or
> three. The TRM for the TH1520 I have shows the standard three (core,
> cfg and mem). I mentioned this on P2 ("clk: thead: Add clock support for
> VO subsystem in T-Head TH1520 SoC"); can you add the missing clock here
> too?
> 
>> Document the integration details including clock, reset, power domain
>> and interrupt assignments. Add a dt-bindings example showing the proper
>> usage of the compatible string "thead,th1520-gpu" along with
>> "img,img-bxm".
>>
>> Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
>> ---
>>  .../bindings/gpu/img,powervr-rogue.yaml       | 39 +++++++++++++++++--
>>  1 file changed, 35 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/gpu/img,powervr-rogue.yaml b/Documentation/devicetree/bindings/gpu/img,powervr-rogue.yaml
>> index bb607d4b1e07..b0d9635704d8 100644
>> --- a/Documentation/devicetree/bindings/gpu/img,powervr-rogue.yaml
>> +++ b/Documentation/devicetree/bindings/gpu/img,powervr-rogue.yaml
>> @@ -12,10 +12,15 @@ maintainers:
>>  
>>  properties:
>>    compatible:
>> -    items:
>> -      - enum:
>> -          - ti,am62-gpu
>> -      - const: img,img-axe # IMG AXE GPU model/revision is fully discoverable
>> +    oneOf:
>> +      - items:
>> +          - enum:
>> +              - ti,am62-gpu
>> +          - const: img,img-axe # IMG AXE GPU model/revision is fully discoverable
>> +      - items:
>> +          - enum:
>> +              - thead,th1520-gpu
>> +          - const: img,img-bxm
> 
> This is going to be the main conflict between this series and the other
> B-Series series I mentioned on the cover letter. One of the main changes
> in that series is to rework how our compatible strings are structured;
> that would make this "thead,th1520-gpu", "img,img-bxm-4-64",
> "img,img-rogue". Would you mind holding this change back until the other
> series lands so we can avoid carrying a second deprecated compatible
> string?

Sure that's completely fine !

> 
>>  
>>    reg:
>>      maxItems: 1
>> @@ -60,6 +65,17 @@ allOf:
>>          clocks:
>>            maxItems: 1
>>  
>> +  - if:
>> +      properties:
>> +        compatible:
>> +          contains:
>> +            const: thead,th1520-gpu
>> +    then:
>> +      properties:
>> +        clocks:
>> +          minItems: 2
>> +          maxItems: 2
> 
> As mentioned before, this doesn't represent the hardware. Please bump to
> 3 and add the missing clock.
> 
>> +
>>  examples:
>>    - |
>>      #include <dt-bindings/interrupt-controller/irq.h>
>> @@ -74,3 +90,18 @@ examples:
>>          interrupts = <GIC_SPI 86 IRQ_TYPE_LEVEL_HIGH>;
>>          power-domains = <&k3_pds 187 TI_SCI_PD_EXCLUSIVE>;
>>      };
>> +
>> +    #include <dt-bindings/clock/thead,th1520-clk-ap.h>
>> +    #include <dt-bindings/power/thead,th1520-power.h>
>> +    #include <dt-bindings/reset/thead,th1520-reset.h>
>> +
>> +    gpu: gpu@fff0000 {
>> +        compatible = "thead,th1520-gpu", "img,img-bxm";
>> +        reg = <0xfff0000 0x1000>;
>> +        interrupt-parent = <&plic>;
>> +        interrupts = <102 IRQ_TYPE_LEVEL_HIGH>;
>> +        clocks = <&clk CLK_GPU_CORE>, <&clk CLK_GPU_CFG_ACLK>;
>> +        clock-names = "core", "mem";
> 
> You have CFG mapped to "mem" here. Out of curiosity, was that mismatch
> required to make things work?

Yeah exactly, I understand that from the GPU perspective there are three
clocks, but only two are programmable from the SoC perspective.

So maybe a placeholder clock should be added in the devicetree then,
since the clock exists, but is reserved.

> 
> Cheers,
> Matt
> 
>> +        power-domains = <&pd TH1520_GPU_PD>;
>> +        resets = <&rst TH1520_RESET_ID_GPU>;
>> +    };
>