Re: [PATCH 2/5] iommu/of: Use device_iommu_mapped()

Joerg Roedel
2018-12-07T09:32:02Z

On Thu, Dec 06, 2018 at 05:42:16PM +0000, Robin Murphy wrote:
> For sure - although I am now wondering whether "mapped" is perhaps a little
> ambiguous in the naming, since the answer to "can I use the API" is yes even
> when the device may currently be attached to an identity/passthrough domain
> or blocked completely, neither of which involve any "mapping". Maybe simply
> "device_has_iommu()" would convey the intent better?

The name is shorter version of:

device_is_behind_an_iommu_remapping_its_dma_transactions()
:)

The name is not perfect, but device_has_iommu() is not better because it
might be considered as a check whether the device itself has an IOMMU
built-in.

In the end an identity-mapping is also still a mapping (if the iommu
needs a page-table for that is an implementation detail), as is a
mapping with no page-table entries at all (blocking). So I think
device_iommu_mapped() is a reasonable choice.

Regards,

Joerg