[Nouveau] [PATCH 2/6] instmem/gk20a: refer to IOMMU physical translation bit

[Alexandre Courbot]

On Thu, Apr 16, 2015 at 8:06 PM, Vince Hsu <vinceh at nvidia.com> wrote:
> Instead of hard-coding the translation bit in subdev driver, we refer to
> the platform data.
>
> Signed-off-by: Vince Hsu <vinceh at nvidia.com>
> ---
>  drm/nouveau/nvkm/subdev/instmem/gk20a.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drm/nouveau/nvkm/subdev/instmem/gk20a.c b/drm/nouveau/nvkm/subdev/instmem/gk20a.c
> index dd0994d9ebfc..69ef5eae3279 100644
> --- a/drm/nouveau/nvkm/subdev/instmem/gk20a.c
> +++ b/drm/nouveau/nvkm/subdev/instmem/gk20a.c
> @@ -89,6 +89,7 @@ struct gk20a_instmem_priv {
>         struct nvkm_mm *mm;
>         struct iommu_domain *domain;
>         unsigned long iommu_pgshift;
> +       unsigned long iommu_phys_addr_bit;
>
>         /* Only used by DMA API */
>         struct dma_attrs attrs;
> @@ -169,8 +170,8 @@ gk20a_instobj_dtor_iommu(struct gk20a_instobj_priv *_node)
>         r = list_first_entry(&_node->mem->regions, struct nvkm_mm_node,
>                              rl_entry);
>
> -       /* clear bit 34 to unmap pages */
> -       r->offset &= ~BIT(34 - priv->iommu_pgshift);
> +       /* clear IOMMU translation bit to unmap pages */
> +       r->offset &= ~BIT(priv->iommu_phys_addr_bit - priv->iommu_pgshift);
>
>         /* Unmap pages from GPU address space and free them */
>         for (i = 0; i < _node->mem->size; i++) {
> @@ -298,8 +299,11 @@ gk20a_instobj_ctor_iommu(struct nvkm_object *parent, struct nvkm_object *engine,
>                 }
>         }
>
> -       /* Bit 34 tells that an address is to be resolved through the IOMMU */
> -       r->offset |= BIT(34 - priv->iommu_pgshift);
> +       /*
> +        * The iommu_phys_addr_bit tells that an address is to be resolved
> +        * through the IOMMU
> +        */
> +       r->offset |= BIT(priv->iommu_phys_addr_bit - priv->iommu_pgshift);
>
>         node->base._mem.offset = ((u64)r->offset) << priv->iommu_pgshift;
>
> @@ -407,6 +411,7 @@ gk20a_instmem_ctor(struct nvkm_object *parent, struct nvkm_object *engine,
>                 priv->domain = plat->gpu->iommu.domain;
>                 priv->mm = plat->gpu->iommu.mm;
>                 priv->iommu_pgshift = plat->gpu->iommu.pgshift;
> +               priv->iommu_phys_addr_bit = plat->gpu->iommu.phys_addr_bit;

Looks good, but I think I would definitely prefer this to be a mask
instead of a bit index, i.e:

    r->offset &= ~(priv->iommu_addr_mask >> priv->iommu_pgshift);

and

    r->offset |= (priv->iommu_addr_mask >> priv->iommu_pgshift);