Hi Joerg, On Monday 26 January 2015 12:00:59 Joerg Roedel wrote: > 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. Could the default domain policy be configured by the IOMMU driver ? The ipmmu- vmsa driver supports four domains only, and serves up to 32 masters, with one group per master. A default of one domain per group wouldn't be usable. -- Regards, Laurent Pinchart -- 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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