Re: [PATCH v5 5/9] iommu/arm-smmu: Attach to host1x context device bus

[Mikko Perttunen]

On 5/16/22 13:44, Robin Murphy wrote:
> On 2022-05-16 11:13, Mikko Perttunen wrote:
> > On 5/16/22 13:07, Will Deacon wrote:
> > > On Mon, May 16, 2022 at 11:52:54AM +0300, cyndis@xxxxxxxx wrote:
> > > > From: Mikko Perttunen <mperttunen@xxxxxxxxxx>
> > > >
> > > > Set itself as the IOMMU for the host1x context device bus, containing
> > > > "dummy" devices used for Host1x context isolation.
> > > >
> > > > Signed-off-by: Mikko Perttunen <mperttunen@xxxxxxxxxx>
> > > > ---
> > > >   drivers/iommu/arm/arm-smmu/arm-smmu.c | 13 +++++++++++++
> > > >   1 file changed, 13 insertions(+)
> > > >
> > > > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c 
> > > > b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > > > index 568cce590ccc..9ff54eaecf81 100644
> > > > --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > > > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > > > @@ -39,6 +39,7 @@
> > > >   #include <linux/amba/bus.h>
> > > >   #include <linux/fsl/mc.h>
> > > > +#include <linux/host1x_context_bus.h>
> > > >   #include "arm-smmu.h"
> > > > @@ -2053,8 +2054,20 @@ static int arm_smmu_bus_init(struct iommu_ops 
> > > > *ops)
> > > >               goto err_reset_pci_ops;
> > > >       }
> > > >   #endif
> > > > +#ifdef CONFIG_TEGRA_HOST1X_CONTEXT_BUS
> > > > +    if (!iommu_present(&host1x_context_device_bus_type)) {
> > > > +        err = bus_set_iommu(&host1x_context_device_bus_type, ops);
> > > > +        if (err)
> > > > +            goto err_reset_fsl_mc_ops;
> > > > +    }
> > > > +#endif
> > > > +
> > > >       return 0;
> > > > +err_reset_fsl_mc_ops: __maybe_unused;
> > > > +#ifdef CONFIG_FSL_MC_BUS
> > > > +    bus_set_iommu(&fsl_mc_bus_type, NULL);
> > > > +#endif
> > >
> > > bus_set_iommu() is going away:
> > >
> > > https://lore.kernel.org/r/cover.1650890638.git.robin.murphy@xxxxxxx
> > >
> > > Will
> >
> > Thanks for the heads-up. Robin had pointed out that this work was 
> > ongoing but I hadn't seen the patches yet. I'll look into it.
>
> Although that *is* currently blocked on the mystery intel-iommu problem 
> that I can't reproduce... If this series is ready to land right now for 
> 5.19 then in principle that might be the easiest option overall. 
> Hopefully at least patch #2 could sneak in so that the compile-time 
> dependencies are ready for me to roll up host1x into the next rebase of 
> "iommu: Always register bus notifiers".
>
> Cheers,
> Robin.

My guess is that the series as a whole is not ready to land in the 5.19 
timeframe, but #2 could be possible.

Thierry, any opinion?

Thanks,
Mikko