On Tue, 2019-06-18 at 18:35 +0200, Matthias Brugger wrote:
>
> On 10/06/2019 14:17, Yong Wu wrote:
> > In the 4GB mode, the physical address is remapped,
> >
> > Here is the detailed remap relationship.
> > CPU PA -> HW PA
> > 0x4000_0000 0x1_4000_0000 (Add bit32)
> > 0x8000_0000 0x1_8000_0000 ...
> > 0xc000_0000 0x1_c000_0000 ...
> > 0x1_0000_0000 0x1_0000_0000 (No change)
> >
> > Thus, we always add bit32 for PA when entering mtk_iommu_map.
> > But in the iova_to_phys, the CPU don't need this bit32 if the
> > PA is from 0x1_4000_0000 to 0x1_ffff_ffff.
> > This patch discards the bit32 in this iova_to_phys in the 4GB mode.
> >
> > Fixes: 30e2fccf9512 ("iommu/mediatek: Enlarge the validate PA range
> > for 4GB mode")
> > Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
> > ---
> > drivers/iommu/mtk_iommu.c | 18 ++++++++++++++++++
> > 1 file changed, 18 insertions(+)
> >
> > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> > index 67cab2d..34f2e40 100644
> > --- a/drivers/iommu/mtk_iommu.c
> > +++ b/drivers/iommu/mtk_iommu.c
> > @@ -119,6 +119,19 @@ struct mtk_iommu_domain {
> >
> > static const struct iommu_ops mtk_iommu_ops;
> >
> > +/*
> > + * In M4U 4GB mode, the physical address is remapped as below:
> > + * CPU PA -> M4U HW PA
> > + * 0x4000_0000 0x1_4000_0000 (Add bit32)
> > + * 0x8000_0000 0x1_8000_0000 ...
> > + * 0xc000_0000 0x1_c000_0000 ...
> > + * 0x1_0000_0000 0x1_0000_0000 (No change)
> > + *
> > + * Thus, We always add BIT32 in the iommu_map and disable BIT32 if PA is >=
> > + * 0x1_4000_0000 in the iova_to_phys.
> > + */
> > +#define MTK_IOMMU_4GB_MODE_PA_140000000 0x140000000UL
> > +
> > static LIST_HEAD(m4ulist); /* List all the M4U HWs */
> >
> > #define for_each_m4u(data) list_for_each_entry(data, &m4ulist, list)
> > @@ -415,6 +428,7 @@ static phys_addr_t mtk_iommu_iova_to_phys(struct iommu_domain *domain,
> > dma_addr_t iova)
> > {
> > struct mtk_iommu_domain *dom = to_mtk_domain(domain);
> > + struct mtk_iommu_data *data = mtk_iommu_get_m4u_data();
> > unsigned long flags;
> > phys_addr_t pa;
> >
> > @@ -422,6 +436,10 @@ static phys_addr_t mtk_iommu_iova_to_phys(struct iommu_domain *domain,
> > pa = dom->iop->iova_to_phys(dom->iop, iova);
> > spin_unlock_irqrestore(&dom->pgtlock, flags);
> >
> > + if (data->plat_data->has_4gb_mode && data->dram_is_4gb &&
> > + pa >= MTK_IOMMU_4GB_MODE_PA_140000000)
> > + pa &= ~BIT_ULL(32);
> > +
>
> Hm, I wonder if we could fix this as first patch in the series, especially before:
> "[PATCH 06/21] iommu/io-pgtable-arm-v7s: Extend MediaTek 4GB Mode"
OK.
>
> This would make it easier for the stable maintainer to cherry-pick the fix.
> Without 100% understanding the code, it seems suspicious to me, that you first
> move the setting of the bit32 and bit33 into v7s and later explicitly clean the
> bits here.
>
> So my take on this is, that patch 6/21 introduced the regression you are trying
> to fix here. As said that is speculation as I don't understand the code in its
> whole.
>
> Any clarification would be useful.
I guess the commit message in [06/21] will be helpful.
In the previous mt8173 and mt2712, the M4U HW support "4GB mode" in
which the range of dram is from 0x4000_0000 to 0x1_3fff_ffff and it was
remapped to 0x1_0000_0000 ~0x1_ffff_ffff(For readable, I have wrote the
re-map relationship into the code in this patch.). but mt8183 don't need
remap the dram address(0x4000_0000 ~ 0x3_ffff_ffff).
In order to unify the code, we add bit32 for "4GB mode". But actually
the PA doesn't always have bit32, thus, I have to remove bit32 when PA >
0x1_4000_0000.
So sorry that the "4GB mode" is a little unreadable and special, And the
4GB patch(30e2fccf9512 ("iommu/mediatek: Enlarge the validate PA range
for 4GB mode") has introduced several fix patches.
>
> Regards,
> Matthias
>
> > return pa;
> > }
> >
> >
>
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