Hi Laurent, On Sun, Jan 25, 2015 at 05:38:22PM +0200, Laurent Pinchart wrote: > IOMMU groups still seem a bit unclear to me. Will Deacon has nicely explained > what they represent in > http://lists.infradead.org/pipermail/linux-arm-kernel/2014-December/310816.html. > The IOMMU core doesn't make groups > mandatory, but requires them in some code paths. > > For example the coldplug device add function add_iommu_group() called for all > devices already registered when bus_set_iommu() is called will try to warn of > devices added multiple times with a WARN_ON(dev->iommu_group). Another example > is the iommu_bus_notifier() function which will call the remove_device() > operation only when dev->iommu_group isn't NULL. > > I'm thus unsure whether groups should be made mandatory, or whether the IOMMU > core should be fixed to make them really optional (or, third option, whether > there's something I haven't understood properly). My plan is to make IOMMU groups mandatory. I am currently preparing and RFC patch-set to introduce default-domains (which will be per group). So when all IOMMU drivers are converted to make use of default domains the iommu groups will be mandatory. Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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