Re: [PATCH v3 1/6] dt-bindings: iommu: arm,smmu: Document interconnects property

On Tue, Aug 11, 2026 at 08:39:41PM +0530, Bibek Kumar Patro wrote:
> 
> 
> On 7/20/2026 8:10 PM, Dmitry Baryshkov wrote:
> > On Mon, Jul 20, 2026 at 07:41:35PM +0530, Bibek Kumar Patro wrote:
> > > 
> > > 
> > > On 7/8/2026 8:48 PM, Bjorn Andersson wrote:
> > > > On Wed, Jul 08, 2026 at 08:22:00PM +0530, Bibek Kumar Patro wrote:
> > > > > 
> > > > > 
> > > > > On 7/7/2026 10:12 PM, Dmitry Baryshkov wrote:
> > > > > > On Tue, Jul 07, 2026 at 06:06:59PM +0530, Bibek Kumar Patro wrote:
> > > > > > > 
> > > > > > > 
> > > > > > > On 7/6/2026 11:09 PM, Dmitry Baryshkov wrote:
> > > > > > > > On Mon, Jul 06, 2026 at 10:26:34PM +0530, Bibek Kumar Patro wrote:
> > > > > > > > > Some SoC implementations require a bandwidth vote on an interconnect
> > > > > > > > > path before the SMMU register space is accessible. Add the optional
> > > > > > > > 
> > > > > > > > Why is it limited only to those SoCs? Is it also applicable to other
> > > > > > > > Qualcomm SoCs?
> > > > > > > > 
> > > > > > > 
> > > > > > > I was hoping to keep this series focused on the core infrastructure
> > > > > > > changes: the bindings, base ICC bandwidth-voting support, and DT
> > > > > > > interconnect properties for the platforms currently supported on
> > > > > > > Qualcomm Linux and have been validated so far.
> > > > > > > 
> > > > > > > The additional targets have not been tested yet, so I'd prefer
> > > > > > > to add their support in a separate follow-up series once validation
> > > > > > > is complete, rather than growing this series further. WDYT?
> > > > > > 
> > > > > > Then it should be a part of the commit message. All SoCs since SDM12345
> > > > > > need to vote on the interconnect (and then, in the cover letter mention
> > > > > > that you convert only a few of the SoCs). We possibly can help with
> > > > > > testing on other platforms.
> > > > > > 
> > > > > 
> > > > > Ack, sounds reasonable.
> > > > > I'll add the first platform onwards which interconnect voting is required in
> > > > > commit description.
> > > > 
> > > > But to what degree is this related to a specific set of platforms? If we
> > > > look ahead, aren't we expecting the list to grow to include all
> > > > platforms in the end - resulting in a lot of noise and churn.
> > > > 
> > > 
> > > We have seen this issue consistently on SM8750 and later platforms, along
> > > with at least one customer-reported instance on SM8550. As a result,
> > > downstream Android implementations already vote for the required
> > > interconnect bandwidth explicitly on these platforms.
> > > 
> > > On Qualcomm Linux targets, we have observed similar issues on Kodiak, with a
> > > few occurrences on Talos as well.
> > > 
> > > My understanding is that the interconnects property remains optional, but in
> > > practice it is needed for Adreno SMMU operation on these platforms.
> > 
> > So, it goes back to Kodiak and Talos. What about SM8150? SDM845? Earlier
> > platforms? Is it limited to MMU-500? A6xx+?
> > 
> 
> Thanks for waiting this long for response,
> I rechecked all the legacy platforms which are present in upstream.

Thanks for your effort and for the very detailed explanations below.

> 
> As per the design it will be applicable to all targets with MMU-500,
> (Even though issue hasn't been reported for all the targets on MMU-500,
> e.g sm8650/sm8250 but the nodes will still be needed).
> It's independent of adreno version i.e A6xx+/A5xx+.

Ack, this sounds reasonable and allows you to easility select if the fix
is to be applied or not by using the generic compat strings.

> 
>   Adreno SMMU — upstream Qualcomm targets
> 
>   SMMU-v2 (QSMMU)
>   Platform   Compatible
>   ---------  ------------------------------------
>   MSM8996    qcom,msm8996-smmu-v2, qcom,adreno-smmu
>   SDM670     qcom,sdm670-smmu-v2, qcom,adreno-smmu
>   SDM845     qcom,sdm845-smmu-v2, qcom,adreno-smmu
>   SC7180     qcom,sc7180-smmu-v2, qcom,adreno-smmu
>   SM6350     qcom,sm6350-smmu-v2, qcom,adreno-smmu
>   SM7150     qcom,sm7150-smmu-v2, qcom,adreno-smmu
>   SM6375     qcom,sm6375-smmu-v2  (apps only, no adreno-smmu node)

	adreno_smmu: iommu@5940000 {
		compatible = "qcom,sm6375-smmu-v2", "qcom,smmu-v2";


>   MSM8998    qcom,msm8998-smmu-v2 (apps only, no adreno-smmu node)

	adreno_smmu: iommu@5040000 {
		compatible = "qcom,msm8998-smmu-v2", "qcom,smmu-v2";


>   SDM630     qcom,sdm630-smmu-v2  (adreno binding to be fixed)

What exactly needs to be fixed?

	kgsl_smmu: iommu@5040000 {
		compatible = "qcom,sdm630-smmu-v2", "qcom,adreno-smmu",
			     "qcom,smmu-v2";


> 
>   SMMU-500 (MMU-500) — with qcom,adreno-smmu
>   Platform   Compatible
>   ---------  ------------------------------------
>   SM6115     qcom,sm6115-smmu-500, qcom,adreno-smmu
>   QCM2290    qcom,qcm2290-smmu-500, qcom,adreno-smmu
>   SM8150     qcom,sm8150-smmu-500, qcom,adreno-smmu
>   SM8250     qcom,sm8250-smmu-500, qcom,adreno-smmu
>   SC8180x    qcom,sc8180x-smmu-500, qcom,adreno-smmu
>   SM8350     qcom,sm8350-smmu-500, qcom,adreno-smmu
>   SC7280     qcom,sc7280-smmu-500, qcom,adreno-smmu  ← our patch series
>   SM8450     qcom,sm8450-smmu-500, qcom,adreno-smmu
>   SC8280xp   qcom,sc8280xp-smmu-500, qcom,adreno-smmu
>   QCS615     qcom,qcs615-smmu-500, qcom,adreno-smmu  ← our patch series
>   SM8550     qcom,sm8550-smmu-500, qcom,adreno-smmu
>   SA8775P    qcom,sa8775p-smmu-500, qcom,adreno-smmu  ← our patch series
>   SM8650     qcom,sm8650-smmu-500, qcom,adreno-smmu
>   QCS8300    qcom,qcs8300-smmu-500, qcom,adreno-smmu  ← our patch series
>   SAR2130P   qcom,sar2130p-smmu-500, qcom,adreno-smmu
>   X1E80100   qcom,x1e80100-smmu-500, qcom,adreno-smmu
>   Glymur     qcom,glymur-smmu-500, qcom,adreno-smmu
>   Milos      qcom,milos-smmu-500, qcom,adreno-smmu
> 
>   SMMU-500 — without qcom,adreno-smmu (apps SMMU only)
>   SDM670     qcom,sdm670-smmu-500  (apps)
>   SDM845     qcom,sdm845-smmu-500  (apps)
>   SC7180     qcom,sc7180-smmu-500  (apps)
>   SM6350     qcom,sm6350-smmu-500  (apps)

All these platforms use a separate v2 QSMMU for Adreno

>   SM8450     qcom,sm8450-smmu-500  (apps)

	adreno_smmu: iommu@3da0000 {
		compatible = "qcom,sm8450-smmu-500", "qcom,adreno-smmu",
			     "qcom,smmu-500", "arm,mmu-500";


>   SC8280xp   qcom,sc8280xp-smmu-500 (apps)

	gpu_smmu: iommu@3da0000 {
		compatible = "qcom,sc8280xp-smmu-500", "qcom,adreno-smmu",
			     "qcom,smmu-500", "arm,mmu-500";

>   SM8750     qcom,sm8750-smmu-500  (adreno-smmu not available yet)

Yes, patches pending, I think.

-- 
With best wishes
Dmitry