Re: [PATCH v2 16/29] iommu/mediatek: Adjust device link when it is sub-common

[Hsin-Yi Wang]

On Fri, Aug 13, 2021 at 3:03 PM Yong Wu <yong.wu@xxxxxxxxxxxx> wrote:
>
> For MM IOMMU, We always add device link between smi-common and IOMMU HW.
> In mt8195, we add smi-sub-common. Thus, if the node is sub-common, we still
> need find again to get smi-common, then do device link.
>
> Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
> ---
>  drivers/iommu/mtk_iommu.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index a4479916ad33..a72241724adb 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -845,6 +845,17 @@ static int mtk_iommu_mm_dts_parse(struct device *dev,
>         if (!smicomm_node)
>                 return -EINVAL;
>
> +       /* Find smi-common again if this is smi-sub-common */
> +       if (of_property_read_bool(smicomm_node, "mediatek,smi_sub_common")) {
> +               of_node_put(smicomm_node); /* put the sub common */
> +
> +               smicomm_node = of_parse_phandle(smicomm_node, "mediatek,smi", 0);

This only checks 1 level here, and does not check if the mediatek,smi
of a sub-common node is not another sub-common node.
So maybe add a check that the updated node here doesn't have
mediatek,smi_sub_common property.

> +               if (!smicomm_node) {
> +                       dev_err(dev, "sub-comm has no common.\n");
> +                       return -EINVAL;
> +               }
> +       }
> +
>         plarbdev = of_find_device_by_node(smicomm_node);
>         of_node_put(smicomm_node);
>         data->smicomm_dev = &plarbdev->dev;
> --
> 2.18.0
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