Re: [PATCH 17/18] media/omap3isp: Clean up IOMMU workaround

Sakari Ailus
2020-08-20T19:56:52Z

On Thu, Aug 20, 2020 at 06:25:19PM +0100, Robin Murphy wrote:
> On 2020-08-20 17:53, Sakari Ailus wrote:
> > Hi Robin,
> >
> > On Thu, Aug 20, 2020 at 04:08:36PM +0100, Robin Murphy wrote:
> > > Now that arch/arm is wired up for default domains and iommu-dma, devices
> > > behind IOMMUs will get mappings set up automatically as appropriate, so
> > > there is no need for drivers to do so manually.
> > >
> > > Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> >
> > Thanks for the patch.
>
> Many thanks for testing so quickly!
>
> > I haven't looked at the details but it seems that this causes the buffer
> > memory allocation to be physically contiguous, which causes a failure to
> > allocate video buffers of entirely normal size. I guess that was not
> > intentional?
>
> Hmm, it looks like the device ends up with the wrong DMA ops, which implies
> something didn't go as expected with the earlier IOMMU setup and default
> domain creation. Chances are that either I missed some subtlety in the
> omap_iommu change, or I've fundamentally misjudged how the ISP probing works
> and it never actually goes down the of_iommu_configure() path in the first
> place. Do you get any messages from the IOMMU layer earlier on during boot?

I do get these:

[ 2.934936] iommu: Default domain type: Translated
[ 2.940917] omap-iommu 480bd400.mmu: 480bd400.mmu registered
[ 2.946899] platform 480bc000.isp: Adding to iommu group 0

--
Sakari Ailus