Subject: Re: [PATCH kernel v8 09/31] powerpc/powernv: Do not set "read" flag if direction==DMA_NONE

From: David Gibson <[email-masked]>
Date: Wed, 15 Apr 2015 17:17:10 +1000

On Fri, Apr 10, 2015 at 04:30:51PM +1000, Alexey Kardashevskiy wrote:
> Normally a bitmap from the iommu_table is used to track what TCE entry
> is in use. Since we are going to use iommu_table without its locks and
> do xchg() instead, it becomes essential not to put bits which are not
> implied in the direction flag.

It's not clear to me from this why lack of locking implies the need to
not put extra bits in.

> This adds iommu_direction_to_tce_perm() (its counterpart is there already)
> and uses it for powernv's pnv_tce_build().
> 
> Signed-off-by: Alexey Kardashevskiy <[email-masked]>

I have no objection to the patch though, so

Reviewed-by: David Gibson <[email-masked]>

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