Re: [PATCH v3 2/2] arm64: dts: qcom: qcs8300: Add device node for gfx_smmu

[Konrad Dybcio]

On 30.01.2025 6:40 AM, Pratyush Brahma wrote:
> 
> On 1/29/2025 7:56 PM, Konrad Dybcio wrote:
>> On 28.01.2025 11:02 AM, Pratyush Brahma wrote:
>>> On 1/9/2025 8:56 PM, Konrad Dybcio wrote:
>>>> On 8.01.2025 1:10 PM, Pratyush Brahma wrote:
>>>>> On 12/30/2024 6:49 PM, Konrad Dybcio wrote:
>>>>>> On 27.12.2024 12:00 PM, Pratyush Brahma wrote:
>>>>>>> Add the device node for gfx smmu that is required for gpu
>>>>>>> specific address translations.
>>>>>>>
>>>>>>> This patch depends on the patch series [1] posted by Imran Shaik
>>>>>>> adding the clock support for gpu.
>>>>>>>
>>>>>>> [1] https://lore.kernel.org/all/802d32f1-ff7e-4d61-83f1-f804ee1750ed@xxxxxxxxxxxxxxxx/
>>>>>>>
>>>>>>> Signed-off-by: Pratyush Brahma <quic_pbrahma@xxxxxxxxxxx>
>>>>>>> ---
>>>>>>>     arch/arm64/boot/dts/qcom/qcs8300.dtsi | 37 +++++++++++++++++++++++++++
>>>>>>>     1 file changed, 37 insertions(+)
>>>>>>>
>>>>>>> diff --git a/arch/arm64/boot/dts/qcom/qcs8300.dtsi b/arch/arm64/boot/dts/qcom/qcs8300.dtsi
>>>>>>> index 80226992a65d..8eb688e2df0a 100644
>>>>>>> --- a/arch/arm64/boot/dts/qcom/qcs8300.dtsi
>>>>>>> +++ b/arch/arm64/boot/dts/qcom/qcs8300.dtsi
>>>>>>> @@ -816,6 +816,43 @@
>>>>>>>                 #power-domain-cells = <1>;
>>>>>>>             };
>>>>>>>     +        adreno_smmu: iommu@3da0000 {
>>>>>>> +            compatible = "qcom,qcs8300-smmu-500", "qcom,adreno-smmu",
>>>>>>> +                   "qcom,smmu-500", "arm,mmu-500";
>>>>>>> +            reg = <0x0 0x3da0000 0x0 0x20000>;
>>>>>>> +            #iommu-cells = <2>;
>>>>>>> +            #global-interrupts = <2>;
>>>>>>> +            dma-coherent;
>>>>>>> +
>>>>>>> +            power-domains = <&gpucc GPU_CC_CX_GDSC>;
>>>>>>> +            clocks = <&gcc GCC_GPU_MEMNOC_GFX_CLK>,
>>>>>>> +                 <&gcc GCC_GPU_SNOC_DVM_GFX_CLK>,
>>>>>>> +                 <&gpucc GPU_CC_AHB_CLK>,
>>>>>>> +                 <&gpucc GPU_CC_HLOS1_VOTE_GPU_SMMU_CLK>,
>>>>>>> +                 <&gpucc GPU_CC_CX_GMU_CLK>,
>>>>>>> +                 <&gpucc GPU_CC_HUB_CX_INT_CLK>,
>>>>>>> +                 <&gpucc GPU_CC_HUB_AON_CLK>;
>>>>>>> +            clock-names = "gcc_gpu_memnoc_gfx_clk",
>>>>>>> +                      "gcc_gpu_snoc_dvm_gfx_clk",
>>>>>>> +                      "gpu_cc_ahb_clk",
>>>>>>> +                      "gpu_cc_hlos1_vote_gpu_smmu_clk",
>>>>>>> +                      "gpu_cc_cx_gmu_clk",
>>>>>>> +                      "gpu_cc_hub_cx_int_clk",
>>>>>>> +                      "gpu_cc_hub_aon_clk";
>>>>>> Most of these entries look totally bogus, please make sure you only
>>>>>> reference the ones actually required
>>>>> These entries are exactly similar to the ones we use in sa8775p as well [1] and the usecases
>>>>> haven't changed between qcs8300 and sa8775p.
>>>>>
>>>>> Can you please let me know which entries you find irrelevant here?
>>>> Well, I'm particularly unsure about CX_GMU and the HUB clocks.
>>>> I >>don't think<< they don't have much to do with the SMMU, but please
>>>> check internally with someone who knows for sure
>>> I checked internally and found that these clocks are required for gpu smmu operations
>>> as we don't use interconnect voting mechanism here as we do downstream. Hence the
>>> list of clocks is same across all targets using gpu smmu as described in [1] previously.
>> I managed to dig up some documents too.. It seems you're right, however the order
>> is supposed to be slightly different:
>>
>> GPU_CC_CX_GMU_CLK
>> GPU_CC_HUB_CX_INT_CLK
>> GPU_CC_HLOS1_VOTE_GPU_SMMU_CLK
>> GCC_GPU_MEMNOC_GFX_CLK
>>
>> Unsure if it *actually* matters given we've added them in a random order on a
>> multitude of platforms and there haven't been any visible adverse effects.
> Thanks for checking this. We haven't really adhered to this order in
> most of our platforms and things have been running fine. So I guess it doesn't matter.
> However, I'll still send out the next patchset in the order you've mentioned. Just so that we
> are in consonance, the final order would look like the following. Please correct me if you'd
> prefer otherwise.
> 
>                 clocks = <&gpucc GPU_CC_CX_GMU_CLK>,
>                                <&gpucc GPU_CC_HUB_CX_INT_CLK>,
>                                <&gpucc GPU_CC_HLOS1_VOTE_GPU_SMMU_CLK>,
>                                <&gcc GCC_GPU_MEMNOC_GFX_CLK>,
>                                <&gcc GCC_GPU_SNOC_DVM_GFX_CLK>,
>                                <&gpucc GPU_CC_AHB_CLK>,
>                                <&gpucc GPU_CC_HUB_AON_CLK>;

Looks good, please double-check if it works without clk_ignore_unused

Konrad