[PATCH 0/3] iommu: qcom: Fix the MSM GPU and display with DMA-address based mappings

[Rob Clark]

On Fri, Oct 30, 2026 at 3:05 PM Dmitry Baryshkov
<dmitry.baryshkov at oss.qualcomm.com> wrote:
>
> Rob's drm/msm series [1] writes the addresses dma_map_sgtable() returns
> for the DRM device into the GPU and display page tables, so they have to
> be physical addresses, i.e. the device must not use iommu-dma. On DPU
> platforms that holds, the DRM device has no iommus of its own. On MDP5
> platforms it is the MDP5 device, which ends up with iommu-dma: the GPU
> then fails to start on db410c and sda660 and resets db820c. The last
> two patches give it an identity default domain in qcom_iommu and
> arm-smmu-qcom.
>
> The first patch fixes qcom_iommu's flush_iotlb_all, which never
> invalidated the TLB. Nothing relies on it today, but the series above
> does, hence no Fixes tag.
>
> The patches are independent of [1] and a no-op for the current drm/msm,
> but have to land before it. Tested on top of [1] on db410c, db820c and
> IFC6560 with and without these patches, and on Open-Q 835 (DPU) as a
> control.

Thanks, this should mostly supersede my untested series[1], but I
think msm_iommu.c still needs the same treatment?  Hopefully just the
def_domain_type() part?

BR,
-R

[1] https://lore.kernel.org/all/20261029212344.346069-1-robin.clark@oss.qualcomm.com/

>
> [1] https://lore.kernel.org/r/20261027230452.130031-1-robin.clark@oss.qualcomm.com
>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at oss.qualcomm.com>
> ---
> Dmitry Baryshkov (3):
>       iommu/qcom: Invalidate the TLB in flush_iotlb_all
>       iommu/qcom: Use identity default domains for the MSM GPU and display
>       iommu/arm-smmu-qcom: Use identity default domains for MDP5
>
>  drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c |  7 ++++++-
>  drivers/iommu/arm/arm-smmu/qcom_iommu.c    | 26 ++++++++++++++++++++++++--
>  2 files changed, 30 insertions(+), 3 deletions(-)
> ---
> base-commit: f1ac44c32cba88ad65dcecd4a279661d14e93651
> change-id: 20261030-msm-smmu-identity-6fda3323023b
>
> Best regards,
> --
> With best wishes
> Dmitry
>