Re: [PATCH v10 09/23] iommu/io-pgtable-arm-v7s: Extend to support PA[33:32] for MediaTek

[Robin Murphy]

On 21/08/2019 16:24, Will Deacon wrote:
> On Wed, Aug 21, 2019 at 09:53:12PM +0800, Yong Wu wrote:
> > MediaTek extend the arm v7s descriptor to support up to 34 bits PA where
> > the bit32 and bit33 are encoded in the bit9 and bit4 of the PTE
> > respectively. Meanwhile the iova still is 32bits.
> >
> > Regarding whether the pagetable address could be over 4GB, the mt8183
> > support it while the previous mt8173 don't, thus keep it as is.
> >
> > Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
> > ---
> >   drivers/iommu/io-pgtable-arm-v7s.c | 32 +++++++++++++++++++++++++-------
> >   include/linux/io-pgtable.h         |  7 +++----
> >   2 files changed, 28 insertions(+), 11 deletions(-)
>
> [...]
>
> > @@ -731,7 +747,9 @@ static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
> >   {
> >   	struct arm_v7s_io_pgtable *data;
> >   
> > -	if (cfg->ias > ARM_V7S_ADDR_BITS || cfg->oas > ARM_V7S_ADDR_BITS)
> > +	if (cfg->ias > ARM_V7S_ADDR_BITS ||
> > +	    (cfg->oas > ARM_V7S_ADDR_BITS &&
> > +	     !(cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT)))
>
> Please can you instead change arm_v7s_alloc_pgtable() so that it allows an
> ias of up to 34 when the IO_PGTABLE_QUIRK_ARM_MTK_EXT is set?

You mean oas, right? I believe the hardware *does* actually support a 
32-bit ias as well, but we shouldn't pretend to support that while 
__arm_v7s_alloc_table() still only knows how to allocate normal-sized 
tables.

Robin.

> With that change:
>
> Acked-by: Will Deacon <will@xxxxxxxxxx>
>
> Will