Re: [PATCH 4/6] iommu/qcom: Add support for AArch64 IOMMU pagetables

[Rob Herring <robh@kernel.org>]

On Fri, May 27, 2022 at 11:28:59PM +0200, Konrad Dybcio wrote:
> From: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
> 
> Some IOMMUs associated with some TZ firmwares may support switching
> to the AArch64 pagetable format by sending a "set pagetable format"
> scm command indicating the IOMMU secure ID and the context number
> to switch.
> 
> Add a DT property "qcom,use-aarch64-pagetables" for this driver to
> send this command to the secure world and to switch the pagetable
> format to benefit of the ARM64 IOMMU pagetables, where possible.
> 
> Note that, even though the command should be valid to switch each
> context, the property is made global because:
> 1. It doesn't make too much sense to switch only one or two
>    context(s) to AA64 instead of just the entire thing
> 2. Some IOMMUs will go crazy and produce spectacular results when
>    trying to mix up the pagetables on a per-context basis.
> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
> Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
> Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
> ---
>  .../devicetree/bindings/iommu/qcom,iommu.txt  |  2 +

Bindings should be separate patch.

As you are making multiple changes, please convert this to DT schema 
first.

>  drivers/iommu/arm/arm-smmu/qcom_iommu.c       | 54 +++++++++++++++----
>  2 files changed, 47 insertions(+), 9 deletions(-)