On Mon, Dec 06, 2021 at 02:35:55PM +0100, Joerg Roedel wrote: > > enum iommu_dma_owner type, void *owner_cookie); > > void iommu_device_release_dma_owner(struct device *dev, > > enum iommu_dma_owner type); > > It the owner is a group-wide setting, it should be called with the group > instead of the device. I have seen the group-specific funcitons are > added later, but that leaves the question why the device-specific ones > are needed at all. They aren't really. A lot of bus drivers need helpers to set/release the dma API domain if there is an iommu group, but tegra which actually sets a non-default value would be much better off with just open coding them. > > @@ -621,6 +624,7 @@ struct iommu_group *iommu_group_alloc(void) > > INIT_LIST_HEAD(&group->devices); > > INIT_LIST_HEAD(&group->entry); > > BLOCKING_INIT_NOTIFIER_HEAD(&group->notifier); > > + group->dma_owner = DMA_OWNER_NONE; > > > DMA_OWNER_NONE is also questionable. All devices are always in one > domain, and the default domain is always the one used for DMA-API, so > why isn't the initial value DMA_OWNER_DMA_API? The interesting part is the suppress_auto_claim_dma_owner flag, but it might make more sense to release the dma API ownership for that rather than requesting it if it is not set.
