On 12/03/2012 10:57:29 AM, Sethi Varun-B16395 wrote:
> -----Original Message-----
> From: iommu-boun...@lists.linux-foundation.org [mailto:iommu-
> boun...@lists.linux-foundation.org] On Behalf Of Joerg Roedel
> Sent: Sunday, December 02, 2012 7:33 PM
> To: Sethi Varun-B16395
> Cc: linux-ker...@vger.kernel.org; io...@lists.linux-foundation.org;
Wood
> Scott-B07421; linuxppc-dev@lists.ozlabs.org; Tabi Timur-B04825
> Subject: Re: [PATCH 3/4 v5] iommu/fsl: Add iommu domain attributes
> required by fsl PAMU driver.
>
> Hmm, we need to work out a good abstraction for this.
>
> On Tue, Nov 20, 2012 at 07:24:56PM +0530, Varun Sethi wrote:
> > Added the following domain attributes required by FSL PAMU driver:
> > 1. Subwindows field added to the iommu domain geometry attribute.
>
> Are the Subwindows mapped with full size or do you map only parts
of the
> subwindows?
>
[Sethi Varun-B16395] It's possible to map a part of the subwindow
i.e. size of the mapping can be less than the sub window size.
> > + * This attribute indicates number of DMA subwindows supported
by
> > + * the geometry. If there is a single window that maps the
entire
> > + * geometry, attribute must be set to "1". A value of "0"
implies
> > + * that this mechanism is not used at all(normal paging is
used).
> > + * Value other than* "0" or "1" indicates the actual number of
> > + * subwindows.
> > + */
>
> This semantic is ugly, how about a feature detection mechanism?
>
[Sethi Varun-B16395] A feature mechanism to query the type of IOMMU?
A feature mechanism to determine whether this subwindow mechanism is
available, and what the limits are.
-Scott
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