[PATCH 1/2] omap: iommu: make iva2 iommu selectable

[Guzman Lugo, Fernando]

> -----Original Message-----
> From: Felipe Contreras [mailto:felipe.contreras at gmail.com] 
> Sent: Monday, October 11, 2010 8:00 AM
> To: Hiroshi DOYU
> Cc: linux-omap at vger.kernel.org; greg at kroah.com; 
> felipe.contreras at nokia.com; Guzman Lugo, Fernando; Marathe, 
> Yogesh; linux-arm-kernel at lists.infradead.org
> Subject: Re: [PATCH 1/2] omap: iommu: make iva2 iommu selectable
> 
> On Mon, Oct 11, 2010 at 3:28 PM, Hiroshi DOYU 
> <Hiroshi.DOYU at nokia.com> wrote:
> > From: ext Felipe Contreras <felipe.contreras at gmail.com>
> > Subject: [PATCH 1/2] omap: iommu: make iva2 iommu selectable
> > Date: Mon, 11 Oct 2010 11:53:49 +0200
> >
> >> From: Felipe Contreras <felipe.contreras at nokia.com>
> >>
> >> It seems dsp-link will do this, and tidspbridge too at some point, 
> >> but right now it's not possible to select CONFIG_MPU_BRIDGE_IOMMU.
> >
> > Why does it have to be selectable?
> 
> You mean why is it desirable to turn it off? Right now 
> there's a mess of tidspbridge branches, some work, some 
> don't, some have migrated to iommu, some don't. In mainline 
> all this, plus the status on dsp-link, should be irrelevant, 
> a configuration solves all the issues.
> 
> Once the iommu migration works (haven't managed to get it 
> working myself), and it has been merged into mainline, then 
> we can think about enabling it unconditionally. In the 
> meantime, enabling unconditionally would break the 
> tidspbridge that is in staging (mainline).

What is the problem enabling unconditionally?

The iva2 iommu does not start working until you call iommu_get.
So if for some reason you are using the dspbridge with custom
Iommu implementation it should not cause any collision with
Iommu module.

Regards,
Fernando.

> 
> > Please Cc: linux-arm-kernel at lists.infradead.org too.
> 
> Will do, after you reply the above.
> 
> --
> Felipe Contreras
>