On Mon, Aug 18, 2014 at 06:57:50PM +0200, Joerg Roedel wrote: > On Fri, Aug 01, 2014 at 02:45:13PM +0200, Thierry Reding wrote: > > From: Thierry Reding <[email protected]> > > > > This allows IOMMU drivers to compile even if IOMMU_API is not selected > > and helps improve compile coverage. > > IOMMU drivers usually implement the IOMMU-API, so they have a strong > dependency to it. Why do you want to compile-test an iommu driver > without testing the iommu core-code as well?
It seems like I never got back to you on this. The reason here is that for Tegra the IOMMU is part of a larger IP block. The IP block is primarily a memory controller with a bunch of configuration knobs for arbitration, prioritization and whatnot. A smaller part of the device does the IOMMU translation. Therefore the IOMMU implementation would be part of a larger driver, and having this dummy would reduce the amount of #ifdefs required. bus_set_iommu() is also the only function in include/linux/iommu.h that doesn't have a dummy, so it seemed like a natural thing to do. That said, I can work around this being absent for !IOMMU_API. Thierry
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