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

[barnabas . czeman]

On 2025-12-01 13:26, Konrad Dybcio wrote:
> On 11/30/25 3:50 PM, barnabas.czeman@xxxxxxxxxxxxxx wrote:
> > On 2025-11-17 15:17, Konrad Dybcio wrote:
> > > On 11/17/25 3:02 PM, barnabas.czeman@xxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxxx> 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>;
> > +       };
> > +};
> > +