Re: [PATCH v7 2/4] mmc: sdhci-tegra: Add support to program MC stream ID

[Ulf Hansson]

On Mon, 17 Oct 2022 at 16:11, Thierry Reding <thierry.reding@xxxxxxxxx> wrote:
>
> On Thu, Oct 13, 2022 at 03:43:18PM +0200, Ulf Hansson wrote:
> > On Thu, 13 Oct 2022 at 08:33, Prathamesh Shete <pshete@xxxxxxxxxx> wrote:
> > >
> > > Hi Ulf,
> > >
> > > >> In that case, perhaps we can add a "depends on IOMMU_API" in the Kconfig
> > > >> instead? Or is the tegra driver used on platforms where IOMMU_API could be
> > > >> unset?
> > > Yes it can/will work with IOMMU disabled so its not recommended to add a "depends on" condition in Kconfig.
> >
> > Alright, in that case it looks to me that there are two other options
> > to move forward.
> >
> > 1) Add proper definitions of the struct iommu_fwspec in
> > include/linux/iommu.h even when CONFIG_IOMMU_API is unset. In a way it
> > seems a bit silly to me, to have the iommu stubs around, unless those
> > can be used for cases like this, right!?
>
> I recall that I had proposed a patch for this a long time ago:
>
>         https://lore.kernel.org/all/20191209120005.2254786-3-thierry.reding@xxxxxxxxx/

That looks exactly what we would need!

>
> Given that Joerg had acked it at the time, I think the only reason why
> it never ended up getting merged is because the rest of the series did
> not get enough traction. I wonder if I should peel it out of the series
> and propose it separately.

Yes, please.

>
> I agree it doesn't make any sense to have the stubs to allow compilation
> and then break compilation because users of the stubs will end up
> wanting to dereference the structure.

Thanks for sharing your thoughts around this!

If you submit a new version of the old patch, I would certainly give
it my blessing.

Kind regards
Uffe