Arnd Bergmann
2022-May-18 14:32 UTC
[PATCH V2 5/7] dt-bindings: Add xen,dev-domid property description for xen-grant DMA ops
On Sat, May 7, 2022 at 7:19 PM Oleksandr Tyshchenko <olekstysh at gmail.com> wrote:> > diff --git a/Documentation/devicetree/bindings/virtio/mmio.yaml b/Documentation/devicetree/bindings/virtio/mmio.yaml > index 10c22b5..29a0932 100644 > --- a/Documentation/devicetree/bindings/virtio/mmio.yaml > +++ b/Documentation/devicetree/bindings/virtio/mmio.yaml > @@ -13,6 +13,9 @@ description: > See https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=virtio for > more details. > > +allOf: > + - $ref: /schemas/arm/xen,dev-domid.yaml# > + > properties: > compatible: > const: virtio,mmio > @@ -33,6 +36,10 @@ properties: > description: Required for devices making accesses thru an IOMMU. > maxItems: 1 > > + xen,dev-domid: > + description: Required when Xen grant mappings need to be enabled for device. > + $ref: /schemas/types.yaml#/definitions/uint32 > + > required: > - compatible > - regSorry for joining the discussion late. Have you considered using the generic iommu binding here instead of a custom property? This would mean having a device node for the grant-table mechanism that can be referred to using the 'iommus' phandle property, with the domid as an additional argument. It does not quite fit the model that Linux currently uses for iommus, as that has an allocator for dma_addr_t space, but it would think it's conceptually close enough that it makes sense for the binding. Arnd
Rob Herring
2022-May-18 18:59 UTC
[PATCH V2 5/7] dt-bindings: Add xen,dev-domid property description for xen-grant DMA ops
On Wed, May 18, 2022 at 03:32:27PM +0100, Arnd Bergmann wrote:> On Sat, May 7, 2022 at 7:19 PM Oleksandr Tyshchenko <olekstysh at gmail.com> wrote: > > > > diff --git a/Documentation/devicetree/bindings/virtio/mmio.yaml b/Documentation/devicetree/bindings/virtio/mmio.yaml > > index 10c22b5..29a0932 100644 > > --- a/Documentation/devicetree/bindings/virtio/mmio.yaml > > +++ b/Documentation/devicetree/bindings/virtio/mmio.yaml > > @@ -13,6 +13,9 @@ description: > > See https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=virtio for > > more details. > > > > +allOf: > > + - $ref: /schemas/arm/xen,dev-domid.yaml# > > + > > properties: > > compatible: > > const: virtio,mmio > > @@ -33,6 +36,10 @@ properties: > > description: Required for devices making accesses thru an IOMMU. > > maxItems: 1 > > > > + xen,dev-domid: > > + description: Required when Xen grant mappings need to be enabled for device. > > + $ref: /schemas/types.yaml#/definitions/uint32 > > + > > required: > > - compatible > > - reg > > Sorry for joining the discussion late. Have you considered using the > generic iommu > binding here instead of a custom property? This would mean having a device > node for the grant-table mechanism that can be referred to using the 'iommus' > phandle property, with the domid as an additional argument. > > It does not quite fit the model that Linux currently uses for iommus, > as that has an allocator for dma_addr_t space, but it would think it's > conceptually close enough that it makes sense for the binding.Something common is almost always better. That may also have the issue that fw_devlink will make the 'iommu' driver a dependency to probe. Rob