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

[Yong Wu (吴勇)]

On Tue, 2021-08-24 at 15:35 +0800, Hsin-Yi Wang wrote:
> 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.

Yes. Currently there are only 2 levels. we could confirm if it is sub-
common from if it has "mediatek,smi", then "mediatek,smi_sub_common" is
unnecessary.

Will fix in the next version.

> 
> > +               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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