> From: Jason Gunthorpe > Sent: Thursday, May 5, 2022 11:33 PM > > > /* > > > - * If the group has been claimed already, do not re-attach the default > > > - * domain. > > > + * New drivers should support default domains and so the > > > detach_dev() op > > > + * will never be called. Otherwise the NULL domain indicates the > > > + * translation for the group should be set so it will work with the > > > > translation should be 'blocked'? > > No, not blocked. > > > > + * platform DMA ops. > > > > I didn't get the meaning of the last sentence. > > It is as discussed with Robin, NULL means to return the group back to > some platform defined translation, and in some cases this means > returning back to work with the platform's DMA ops - presumably if it > isn't using the dma api.
This is clearer than the original text. > > > > + /* > > > + * Changing the domain is done by calling attach on the new domain. > > > + * Drivers should implement this so that DMA is always translated by > > > > what does 'this' mean? > > The code below - attach_dev called in a loop for each dev in the group. Yes. > > > > + * either the new, old, or a blocking domain. DMA should never > > > > isn't the blocking domain passed in as the new domain? > > Soemtimes. This is a statement about the required > atomicity. New/old/block are all valid translations during the > operation. Identity is not. but new/old/block are not the same type of classifications. A group has an old domain and a new domain at this transition point, and both old/new domains have a domain type (dma, unmanged, block, identity, etc.). Mixing them together only increases confusion here. > > So, I'm going to leave this patch as-is since it has been tested now > and we need to get the series back into iommu-next ASAP. > Agree. Just hope some improvements on the code comment. But either way given no more code change: Reviewed-by: Kevin Tian <kevin.t...@intel.com> _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
