Re: [PATCH 2/4] clk: qcom: gcc: Add support for Global Clock controller found on MSM8940

[barnabas.czeman@mainlining.org]

On 2025-12-01 13:26, Konrad Dybcio wrote:
> On 11/30/25 3:50 PM, barnabas.czeman@mainlining.org wrote:
>> On 2025-11-17 15:17, Konrad Dybcio wrote:
>>> On 11/17/25 3:02 PM, barnabas.czeman@mainlining.org wrote:
>>>> On 2025-11-17 13:17, Konrad Dybcio wrote:
>>>>> On 11/17/25 9:51 AM, Barnabás Czémán wrote:
>>>>>> 
>>>>>> 
>>>>>> On 17 November 2025 09:03:53 CET, Taniya Das 
>>>>>> <taniya.das@oss.qualcomm.com> wrote:
>>>>>>> 
>>>>>>> 
>>>>>>> On 11/17/2025 3:05 AM, Barnabás Czémán wrote:
>>>>>>>> 
>>>>>>>> +static struct clk_branch gcc_ipa_tbu_clk = {
>>>>>>>> +    .halt_reg = 0x120a0,
>>>>>>>> +    .halt_check = BRANCH_VOTED,
>>>>>>>> +    .clkr = {
>>>>>>>> +        .enable_reg = 0x4500c,
>>>>>>>> +        .enable_mask = BIT(16),
>>>>>>>> +        .hw.init = &(struct clk_init_data){
>>>>>>>> +            .name = "gcc_ipa_tbu_clk",
>>>>>>>> +            .ops = &clk_branch2_ops,
>>>>>>>> +        },
>>>>>>>> +    },
>>>>>>>> +};
>>>>>>>> +
>>>>>>> 
>>>>>>> Is the TBU clock used on 8940 by a SMMU driver?
>>>>>> As far as I know no MSM8940 is using same smmu driver and bindings 
>>>>>> like MSM8937.
>>>>> 
>>>>> On msm8939, the clock needed to be turned on for the GPU SMMU
>>>> I have not got any qcom-iommu issues on 8940 but i think it could 
>>>> come when i try to add ipa2 driver
>>>> for the SoC until i do not know where to check it.
>>> 
>>> I can't find a definitive answer, but it's most certainly going to be
>>> necessary to turn it on
>>> 
>>> Konrad
>> 
>> I have enabled ipa2-lite for 8940 at downstream and it can cause gpu 
>> to crash.
> 
> Really!?
> 
> FWIW the clock on 8939 is called GCC_*GFX*_TBU_CLK so it being related
> made more sense. Here, I see no connection :/
> 
> Konrad

I have find out the issue was caused by the interconnect, removing 
sync_state callback
makes the ipa driver working, the ipa tbu clock do not needed to be 
enabled by smmu.
> 
>> I have tried to add TBU clock for apps_iommu but it not fixing the 
>> issue.
>> 
>> Here are the iommu changes based on 8937 apps_iommu node:
>> +&apps_iommu {
>> +       clocks = <&gcc GCC_SMMU_CFG_CLK>,
>> +                <&gcc GCC_APSS_TCU_CLK>,
>> +                <&gcc MSM8940_GCC_IPA_TBU_CLK>;
>> +       clock-names = "iface",
>> +                     "bus",
>> +                     "tbu";
>> +
>> +       /* IPA */
>> +       iommu-ctx@18000 {
>> +               compatible = "qcom,msm-iommu-v1-ns";
>> +               reg = <0x18000 0x1000>;
>> +               interrupts = <GIC_SPI 115 IRQ_TYPE_LEVEL_HIGH>;
>> +       };
>> +};
>> +
>>