Hi Hari,
From: "ext Kanigeri, Hari" <[email protected]>
Subject: RE: [RFC] dspbridge: staging todo list
Date: Mon, 27 Apr 2009 05:05:38 +0200
> Hi,
>
> > This DMM feature should be replaced with "omap iommu" driver which
> > commonly supports omap iommu feature. Currently it supports just a
> > mapping of in-kernel buffers(contiguous/discontiguous), but will be
> > extened to an user buffer soon. Anyway, "bitmap_find_free_region"
> > would bring better performance if the number of VMAs becomes huge.
> >
>
> -- DMM is dynamic memory mapping, where DSP VA is mapped to Physical
> address of the buffers allocated by Multimedia applications. At
> present, Bridge is using its own version of MMU module for mapping
> the DSP VA to physical address, and this Bridge's MMU module can be
> replaced with the omap iommu. But before we do that, following
> things need to happen:
>
> - The iommu should reside in linux-omap tree :)
Tony may keep it on one of the l-o branches. Anyway, I'll send them
again to Russell.
> - IOMMU module provides support for preservation of TLB
> entries.
Yes, it's necessary for the performance.
> - IOMMU module provides support for notification of MMU
> faults.
Actually the mmu fault hander can be set by a client module, but at
present, the registration interface is missing. I'll add this
interface.
> I did some basic sanity testing in Bridge by replacing the Bridge's
> MMU module with the iommu module and the above items need to happen
> before we migrate to use iommu.
Thank you for your evaluation. I'll send the update version of iommu
patchset soon.
Hiroshi DOYU
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