On Wed, Feb 06, 2019 at 05:56:02PM +0300, Dmitry Osipenko wrote: > > We don't have an IOMMU attached to I2C or APBDMA, so this can't happen > > and even if we had an IOMMU attached, all we care about is the device's > > DMA address space, which means IOVA space, and that would still be > > guaranteed to be contiguous, according to the above. > > Yes, but doesn't T186+ have IOMMU support for the DMA controller? Even if it did, why would that matter? The device would only see IOVA space, the CPU for a normal driver only sees kernel virtual space. Forced contiguous space only makes sense when you have access by CPU physical address, which should not happen for "normal" device drivers.
