RE: [PATCH 2/2] iommu/ipmmu-vmsa: Add support for r8a779a0

[Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>]

Hi Geert-san,

> From: Geert Uytterhoeven, Sent: Tuesday, September 7, 2021 12:34 AM
> 
> Hi Shimoda-san,
> 
> On Wed, Sep 1, 2021 at 12:27 PM Yoshihiro Shimoda
> <yoshihiro.shimoda.uh@renesas.com> wrote:
> > Add support for r8a779a0 (R-Car V3U). The IPMMU hardware design
> > of this SoC differs than others. So, add a new ipmmu_features for it.
> >
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> 
> > --- a/drivers/iommu/ipmmu-vmsa.c
> > +++ b/drivers/iommu/ipmmu-vmsa.c
> 
> > @@ -922,6 +922,20 @@ static const struct ipmmu_features ipmmu_features_rcar_gen3 = {
> >         .utlb_offset_base = 0,
> >  };
> >
> > +static const struct ipmmu_features ipmmu_features_r8a779a0 = {
> > +       .use_ns_alias_offset = false,
> > +       .has_cache_leaf_nodes = true,
> > +       .number_of_contexts = 8,
> 
> Shouldn't this be 16?
> Or do you plan to add support for more than 8 contexts later, as that
> would require increasing IPMMU_CTX_MAX, and updating ipmmu_ctx_reg()
> to handle the second bank of 8 contexts?

I would like to add support for more than 8 contexts later because
I realized that ctx_offset_{base,stride} are not suitable for the second bank
of 8 contexts...

> Regardless, I assume this will still work when when limiting to 8
> contexts, so
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Thank you for your review!

Best regards,
Yoshihiro Shimoda

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