RE: [PATCH 1/3] iommu/fsl: Fix PAMU window size check.

[Varun Sethi]

> -----Original Message-----
> From: Joerg Roedel [mailto:joro@xxxxxxxxxx]
> Sent: Friday, July 04, 2014 4:15 PM
> To: Sethi Varun-B16395
> Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> linuxppc-dev@xxxxxxxxxxxxxxxx; alex.williamson@xxxxxxxxxx
> Subject: Re: [PATCH 1/3] iommu/fsl: Fix PAMU window size check.
> 
> On Tue, Jun 24, 2014 at 07:27:15PM +0530, Varun Sethi wrote:
> >  	/* window size is 2^(WSE+1) bytes */
> > -	return __ffs(addrspace_size) - 1;
> > +	return fls64(addrspace_size) - 2;
> 
> This looks bogus, why do you replace ffs (find-first-bit) by fls (find-
> last-bit)?
> 
Address space size is always a power of 2. This change was required to handle address sizes > 32bit width on 32 bit architectures.

-Varun

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