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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Leonardo Bras <leobras.c@gmail.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Alexey Kardashevskiy <aik@ozlabs.ru>, brking@linux.vnet.ibm.com
Cc:     linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/1] powerpc/iommu: Enable remaining IOMMU Pagesizes
 present in LoPAR
In-Reply-To: <eed000bfa26686f616b91a7ac5a54ff8e3f2cbd0.camel@gmail.com>
References: <20210407195613.131140-1-leobras.c@gmail.com>
 <87im4xe3pk.fsf@mpe.ellerman.id.au>
 <942acb9b23d87594d0b758cc0daf713be836f8e6.camel@gmail.com>
 <eed000bfa26686f616b91a7ac5a54ff8e3f2cbd0.camel@gmail.com>
Date:   Thu, 08 Apr 2021 19:08:22 +1000
Message-ID: <87blapdtyx.fsf@mpe.ellerman.id.au>
MIME-Version: 1.0
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Leonardo Bras <leobras.c@gmail.com> writes:
> On Thu, 2021-04-08 at 03:20 -0300, Leonardo Bras wrote:
>> > > +#define QUERY_DDW_PGSIZE_4K	0x01
>> > > +#define QUERY_DDW_PGSIZE_64K	0x02
>> > > +#define QUERY_DDW_PGSIZE_16M	0x04
>> > > +#define QUERY_DDW_PGSIZE_32M	0x08
>> > > +#define QUERY_DDW_PGSIZE_64M	0x10
>> > > +#define QUERY_DDW_PGSIZE_128M	0x20
>> > > +#define QUERY_DDW_PGSIZE_256M	0x40
>> > > +#define QUERY_DDW_PGSIZE_16G	0x80
>> > 
>> > I'm not sure the #defines really gain us much vs just putting the
>> > literal values in the array below?
>> 
>> My v1 did not use the define approach, what do you think of that?
>> http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20210322190943.715368-1-leobras.c@gmail.com/
>> 
>> 
> (of course, it would be that without the pageshift defines also, using
> the __builtin_ctz() approach suggested by Alexey.)

Yeah I think I like that better.

cheers