Re: [PATCH 10/18] iommu/msm: Add IOMMU_DOMAIN_DMA support

[Rob Clark]

On Thu, Aug 20, 2020 at 9:58 AM Robin Murphy <robin.murphy@xxxxxxx> wrote:
>
> On 2020-08-20 16:55, Rob Clark wrote:
> > Side note, I suspect we'll end up needing something like
> > 0e764a01015dfebff8a8ffd297d74663772e248a .. if someone can dig a 32b
> > device out of the closet and dust it off, the fix is easy enough.
> > Just wanted to mention that here so anyone with a 32b device could
> > find what is needed.
>
> FWIW there shouldn't be any material change here - the generic default
> domain is installed under the same circumstances as the Arm
> dma_iommu_mapping was, so if any platform does have an issue, then it
> should already have started 4 years with f78ebca8ff3d ("iommu/msm: Add
> support for generic master bindings").

ok, it has, I guess, been a while since playing with 32b things..
someone on IRC had mentioned a problem that sounded like what
0e764a01015dfebff8a8ffd297d74663772e248a solved, unless they disabled
some ARCH_HAS_xyz thing (IIRC), which I guess is related..

BR,
-R

> Robin.
>
> >
> > BR,
> > -R
> >
> > On Thu, Aug 20, 2020 at 8:09 AM Robin Murphy <robin.murphy@xxxxxxx> wrote:
> >>
> >> Now that arch/arm is wired up for default domains and iommu-dma,
> >> implement the corresponding driver-side support for DMA domains.
> >>
> >> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
> >> ---
> >>   drivers/iommu/msm_iommu.c | 7 ++++++-
> >>   1 file changed, 6 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/iommu/msm_iommu.c b/drivers/iommu/msm_iommu.c
> >> index 3615cd6241c4..f34efcbb0b2b 100644
> >> --- a/drivers/iommu/msm_iommu.c
> >> +++ b/drivers/iommu/msm_iommu.c
> >> @@ -8,6 +8,7 @@
> >>   #include <linux/kernel.h>
> >>   #include <linux/init.h>
> >>   #include <linux/platform_device.h>
> >> +#include <linux/dma-iommu.h>
> >>   #include <linux/errno.h>
> >>   #include <linux/io.h>
> >>   #include <linux/io-pgtable.h>
> >> @@ -314,13 +315,16 @@ static struct iommu_domain *msm_iommu_domain_alloc(unsigned type)
> >>   {
> >>          struct msm_priv *priv;
> >>
> >> -       if (type != IOMMU_DOMAIN_UNMANAGED)
> >> +       if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
> >>                  return NULL;
> >>
> >>          priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> >>          if (!priv)
> >>                  goto fail_nomem;
> >>
> >> +       if (type == IOMMU_DOMAIN_DMA && iommu_get_dma_cookie(&priv->domain))
> >> +               goto fail_nomem;
> >> +
> >>          INIT_LIST_HEAD(&priv->list_attached);
> >>
> >>          priv->domain.geometry.aperture_start = 0;
> >> @@ -339,6 +343,7 @@ static void msm_iommu_domain_free(struct iommu_domain *domain)
> >>          struct msm_priv *priv;
> >>          unsigned long flags;
> >>
> >> +       iommu_put_dma_cookie(domain);
> >>          spin_lock_irqsave(&msm_iommu_lock, flags);
> >>          priv = to_msm_priv(domain);
> >>          kfree(priv);
> >> --
> >> 2.28.0.dirty
> >>
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