Subject: Re: [PATCH v2 06/18] powerpc/powernv: Use it_page_shift in TCE build

From: Gavin Shan <[email-masked]>
Date: Wed, 23 Jul 2014 14:00:40 +1000

On Wed, Jul 23, 2014 at 01:05:52PM +1000, Alexey Kardashevskiy wrote:
>This makes use of iommu_table::it_page_shift instead of TCE_SHIFT and
>TCE_RPN_SHIFT hardcoded values.
>
>Signed-off-by: Alexey Kardashevskiy <[email-masked]>

Reviewed-by: Gavin Shan <[email-masked]>

>---
> arch/powerpc/platforms/powernv/pci.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
>diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
>index f91a4e5..b6cb996 100644
>--- a/arch/powerpc/platforms/powernv/pci.c
>+++ b/arch/powerpc/platforms/powernv/pci.c
>@@ -564,10 +564,11 @@ static int pnv_tce_build(struct iommu_table *tbl, long index, long npages,
> 		proto_tce |= TCE_PCI_WRITE;
>
> 	tces = tcep = ((__be64 *)tbl->it_base) + index - tbl->it_offset;
>-	rpn = __pa(uaddr) >> TCE_SHIFT;
>+	rpn = __pa(uaddr) >> tbl->it_page_shift;
>

I'm not sure for 100%. It might be worthy to have some check somewhere:

	WARN_ON(uaddr & ((1ull << tbl->it_page_shift) - 1))

The "uaddr" are required to be "0x1ull << tbl->it_page_shift" aligned :-)

Thanks,
Gavin

> 	while (npages--)
>-		*(tcep++) = cpu_to_be64(proto_tce | (rpn++ << TCE_RPN_SHIFT));
>+		*(tcep++) = cpu_to_be64(proto_tce |
>+				(rpn++ << tbl->it_page_shift));
>
> 	/* Some implementations won't cache invalid TCEs and thus may not
> 	 * need that flush. We'll probably turn it_type into a bit mask
>-- 
>2.0.0
>