Re: [PATCH 1/9] iommu/of: Drop early initialisation hooks

[JeffyChen]

Hi Robin,

Thnaks for your reply.

On 01/11/2018 08:24 PM, Robin Murphy wrote:
> Hi Jeffy,
>
> On 11/01/18 11:14, JeffyChen wrote:
> > Hi Marek,
> >
> > Thanks for your reply.
> >
> > On 01/11/2018 05:40 PM, Marek Szyprowski wrote:
> > > Hi Jeffy,
> > >
> > > On 2018-01-11 09:22, Jeffy Chen wrote:
> > > > With the probe-deferral mechanism, early initialisation hooks are no
> > > > longer needed.
> > > >
> > > > Suggested-by: Robin Murphy <robin.murphy@xxxxxxx>
>
> In fact, shortly after I said that I had a "how hard can it be?" moment
> and took a crack at it myself - sorry, I should probably have cc'd you
> on that series[1].

hmmm, i'll drop this patch in the next version.

and maybe rebase my patch[9] (iommu/rockchip: Use OF_IOMMU to attach 
devices automatically) on that series
> > > > Signed-off-by: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx>
> > > > ---
> > > >
> > > >   drivers/iommu/arm-smmu-v3.c  |  2 +-
> > > >   drivers/iommu/arm-smmu.c     | 12 ++++++------
> > > >   drivers/iommu/exynos-iommu.c |  2 +-
> > >
> > > For Exynos IOMMU:
> > > Acked-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> > >
> > > IPMMU and MSM IOMMU are no longer multi-platform safe after this patch.
> > > It breaks them in the same way as my commit 928055a01b3f ("iommu/exynos:
> > > Remove custom platform device registration code") broke Exynos IOMMU.
> > >
> > > You need a similar fix for them:
> > > https://www.spinics.net/lists/arm-kernel/msg627648.html
> >
> > hmmm, right, i did saw this fix in the rockchip iommu driver too.
> >
> > and there're also some other iommu drivers put bus_set_iommu in their
> > probe() to avoid that.
> >
> > maybe we can do it in the iommu framework?
> >
> > for example:
> > 1/ add a bus type member to struct iommu_device
> > 2/ and a iommu_device_set_bus()
> > 3/ do the bus_set_iommu stuff in iommu_device_register()
> > 4/ undo bus_set_iommu in iommu_device_unregister()
>
> Ultimately we'd like to get rid of the bus relationship altogether, so I
> don't think it's really worth adding more infrastructure around it.
> Having of-iommu-based drivers set bus ops at probe time, and others
> conditionally from an initcall, is pretty clean and simple, so I'd
> rather stick with that approach for now.
ok, make sense:)
> Robin.
>
> [1]
> https://lists.linuxfoundation.org/pipermail/iommu/2018-January/025395.html