Re: [PATCH 00/12] iommu: qcom_iommu: implement support for instances on MSM8974

On Mon, Aug 10, 2026 at 12:16:19PM +0200, Luca Weiss wrote:
> Hi Dmitry,
> 
> Many thanks for working on this and sending this patch series!
> 
> On Sun Aug 9, 2026 at 10:15 PM CEST, Dmitry Baryshkov wrote:
> > Qualcomm MSM8974 platform has five SMMU instances, used by display, GPU,
> > Venus, VFE (camera) and JPEG encoder. Each of them follows ARM SMMU v1
> > spec, however they differ from other Qualcomm platforms in the
> > implementation-specific registers and also in interaction with TZ.
> > Venus, MDP and VFE SMMUs are secured and require programming only of
> > CBs, while GPU and JPEG require full programming.
> >
> > This series skips IOMMUs which can't be tested right now (VFE and JPEG),
> > and adds only MDP, GPU and Venus (although untested, it is required for
> > display to work) SMMU instances.
> 
> I do have a patch series (sent years ago to the mailing lists as well)
> for CAMSS so I can definitely test this in the future.

Ok, let's land these first, unless VFE IOMMU blocks display on your
platform (Venus was blocking display on APQ8074 DragonBoard).

> > Note, to get display to work properly one fix is necessary, [1]
> >
> > [1] https://patch.msgid.link/[email protected]
> 
> I've applied this series on v7.2-rc7, with the extra commits between
> that and linux-next for qcom_iommu.c backported so that your series
> applies without conflicts.
> 
> So far I'm stuck with the GPU not being able to probe, adding some
> printk's shows that in msm_iommu_new() the call for
> iommu_attach_device() is failing.
> 
> [    5.971154] msm_mdp fd900100.display-controller: failed to load adreno gpu
> [    5.972991] msm_mdp fd900100.display-controller: failed to bind fdb00000.gpu (ops a3xx_ops [msm]): -16
> [    5.974073] msm_mdp fd900100.display-controller: adev bind failed: -16
> [    5.974152] panel-s6d6fa1 fd922800.dsi.0: error -EBUSY: Failed to attach to DSI host
> [    5.974230] panel-s6d6fa1 fd922800.dsi.0: probe with driver panel-s6d6fa1 failed with error -16

See the patch [1], it's picked up for 7.3


[1] https://lore.kernel.org/r/[email protected]

> 
> ~ # dmesg | grep iommu
> [    0.127014] iommu: Default domain type: Translated
> [    0.127052] iommu: DMA domain TLB invalidation policy: strict mode
> [    0.739899] platform fdb00000.gpu: Adding to iommu group 0
> [    0.741358] qcom-iommu fdc84000.iommu: iommu sec: pgtable size: 90112
> [    6.006877] platform fd900100.display-controller: Adding to iommu group 1
> 
> Have you seen any issues like this?

-- 
With best wishes
Dmitry