Re: [PATCH v3 3/3] arm64: dts: qcom: sm8750: Add GPU clock & IOMMU nodes

[Konrad Dybcio]

On 2/21/26 7:22 PM, Akhil P Oommen wrote:
> On 2/20/2026 11:24 AM, Taniya Das wrote:
>> From: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>
>>
>> Add the GPU_CC and GX_CC (brand new! as far as we're concerned, this
>> is simply a separate block housing the GX GDSC) nodes, required to
>> power up the graphics-related hardware.
>>
>> Make use of it by enabling the associated IOMMU as well. The GPU itself
>> needs some more work and will be enabled later.
>>
>> Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>
>> Co-developed-by: Taniya Das <taniya.das@xxxxxxxxxxxxxxxx>
>> Signed-off-by: Taniya Das <taniya.das@xxxxxxxxxxxxxxxx>
>> ---
>>  arch/arm64/boot/dts/qcom/sm8750.dtsi | 64 ++++++++++++++++++++++++++++++++++++
>>  1 file changed, 64 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/sm8750.dtsi b/arch/arm64/boot/dts/qcom/sm8750.dtsi
>> index f56b1f889b857a28859910f5c4465c8ce3473b00..0cc931d0bc96e9563ce4e7989ecd4ba50bd424f8 100644
>> --- a/arch/arm64/boot/dts/qcom/sm8750.dtsi
>> +++ b/arch/arm64/boot/dts/qcom/sm8750.dtsi
>> @@ -4,7 +4,9 @@
>>   */
>>  
>>  #include <dt-bindings/clock/qcom,rpmh.h>
>> +#include <dt-bindings/clock/qcom,kaanapali-gxclkctl.h>
>>  #include <dt-bindings/clock/qcom,sm8750-gcc.h>
>> +#include <dt-bindings/clock/qcom,sm8750-gpucc.h>
>>  #include <dt-bindings/clock/qcom,sm8750-tcsr.h>
>>  #include <dt-bindings/clock/qcom,sm8750-videocc.h>
>>  #include <dt-bindings/dma/qcom-gpi.h>
>> @@ -3001,6 +3003,30 @@ videocc: clock-controller@aaf0000 {
>>  			#power-domain-cells = <1>;
>>  		};
>>  
>> +		gxclkctl: clock-controller@3d64000 {
>> +			compatible = "qcom,sm8750-gxclkctl";
>> +			reg = <0x0 0x03d64000 0x0 0x6000>;
>> +
>> +			power-domains = <&rpmhpd RPMHPD_GFX>,
>> +					<&rpmhpd RPMHPD_GMXC>,
>> +					<&gpucc GPU_CC_CX_GDSC>;
>> +
>> +			#power-domain-cells = <1>;
>> +		};
>> +
>> +		gpucc: clock-controller@3d90000 {
>> +			compatible = "qcom,sm8750-gpucc";
>> +			reg = <0x0 0x03d90000 0x0 0x9800>;
>> +
>> +			clocks = <&bi_tcxo_div2>,
>> +				 <&gcc GCC_GPU_GPLL0_CLK_SRC>,
>> +				 <&gcc GCC_GPU_GPLL0_DIV_CLK_SRC>;
>> +
>> +			#clock-cells = <1>;
>> +			#reset-cells = <1>;
>> +			#power-domain-cells = <1>;
> 
> On Pakala and newer GPUs, we need to scale GMU (which is connected to
> the CX GDSC) freq. Is this DT description sufficient to allow scaling of
> GMU OPP?

No, certainly not.

I see that GPU_CC on this one is exclusively powered by VDD_CX, with
some MXA backing, so the natural course of action would be to add a
RPMHPD_CX power-domains handle here. Then, voting on the CX_GDSC will
propagate the performance state to RPMHPD_CX.

Taniya, I see there's also some MXA backing. Do we need to scale it,
or is "just ON" fine here?

Konrad