Re: [PATCH v4 09/24] iommu/io-pgtable-arm-v7s: Clear LVL_SHIFT/BITS macro instead of the formula

Yong Wu
2020-11-27T06:33:14Z

On Thu, 2020-11-26 at 16:03 +0000, Robin Murphy wrote:
> On 2020-11-11 12:38, Yong Wu wrote:
> > The current _ARM_V7S_LVL_BITS/ARM_V7S_LVL_SHIFT use a formula to calculate
> > the corresponding value for level1 and level2 to pretend the code sane.
> > Actually their level1 and level2 values are different from each other.
> > This patch only clear the two macro. No functional change.
>
> Grammar nit: to "clear" the macro sounds like you're making it empty or
> removing it entirely; I think you mean to say "clarify" here. English is
> the worst language sometimes... :)

Thanks for the review. Feel free to tell me if some words is not fit:)

I will use "clarify" in the title.

>
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
>
> > Suggested-by: Robin Murphy <robin.murphy@arm.com>
> > Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> > ---
> > drivers/iommu/io-pgtable-arm-v7s.c | 8 +++-----
> > 1 file changed, 3 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
> > index 4d0aa079470f..58cc201c10a3 100644
> > --- a/drivers/iommu/io-pgtable-arm-v7s.c
> > +++ b/drivers/iommu/io-pgtable-arm-v7s.c
> > @@ -44,13 +44,11 @@
> >
> > /*
> > * We have 32 bits total; 12 bits resolved at level 1, 8 bits at level 2,
> > - * and 12 bits in a page. With some carefully-chosen coefficients we can
> > - * hide the ugly inconsistencies behind these macros and at least let the
> > - * rest of the code pretend to be somewhat sane.
> > + * and 12 bits in a page.
> > */
> > #define ARM_V7S_ADDR_BITS 32
> > -#define _ARM_V7S_LVL_BITS(lvl) (16 - (lvl) * 4)
> > -#define ARM_V7S_LVL_SHIFT(lvl) (ARM_V7S_ADDR_BITS - (4 + 8 * (lvl)))
> > +#define _ARM_V7S_LVL_BITS(lvl) ((lvl) == 1 ? 12 : 8)
> > +#define ARM_V7S_LVL_SHIFT(lvl) ((lvl) == 1 ? 20 : 12)
> > #define ARM_V7S_TABLE_SHIFT 10
> >
> > #define ARM_V7S_PTES_PER_LVL(lvl) (1 << _ARM_V7S_LVL_BITS(lvl))
> >