> -----Original Message----- > From: Yoder Stuart-B08248 > Sent: Friday, March 01, 2013 9:52 PM > To: Alexey Kardashevskiy; Sethi Varun-B16395 > Cc: Kumar Gala; Benjamin Herrenschmidt; io...@lists.linux-foundation.org; > linuxppc-dev@lists.ozlabs.org list; linux-ker...@vger.kernel.org list; > Wood Scott-B07421; Joerg Roedel; Paul Mackerras; David Gibson; Alex > Williamson > Subject: RE: [PATCH 1/6 v8] iommu/fsl: Store iommu domain information > pointer in archdata. > > > > > -----Original Message----- > > From: Alexey Kardashevskiy [mailto:a...@ozlabs.ru] > > Sent: Friday, March 01, 2013 4:07 AM > > To: Sethi Varun-B16395 > > Cc: Kumar Gala; Benjamin Herrenschmidt; > > io...@lists.linux-foundation.org; linuxppc-dev@lists.ozlabs.org list; > > linux-ker...@vger.kernel.org list; Wood Scott-B07421; Yoder > > Stuart-B08248; Joerg Roedel; Paul Mackerras; David Gibson; Alex > > Williamson > > Subject: Re: [PATCH 1/6 v8] iommu/fsl: Store iommu domain information > pointer in archdata. > > > > btw the device struct already has a pointer to its iommu_group, and > > the iommu_group struct itself has a pointer void *iommu_data which you > > could use for anything you want (iommu_group_get_iommudata(), > > iommu_group_set_iommudata()). > > > > By design you are expected to add iommu groups to a domain but not > > devices so I am not so sure that you really need a pointer to domain > > in the device struct. > > Well, at the lowest level the IOMMU API does attach devices to domains-- > i.e. > API attach_dev(). So, it seems to conceptually make sense to have a ptr > from the device to the associated domain. When you implement > attach_dev() you need to be able to see whether the device is already > attached to > a domain. Adding a couple of levels of indirection...from device to > group to domain...doesn't seems to make things simpler or better IMHO. > > x86 keeps a pointer to the domain in device archdata and since there is a > direct correlation between a device and domain I'd rather see it where > this patch has it. >
As Stuart stated this allows us to maintain the device <-> domain relationship at the lowest level. -Varun _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
