23.04.2021 19:32, Thierry Reding пишет: > Hi, > > this is an updated proposal to solve the problem of passing memory > regions that are actively being accessed during boot. The particular > use-case that I need this for is when the bootloader has set up the > display controller to scan out a boot splash screen. During boot the > DMA/IOMMU glue code will attach devices to an IOMMU domain and by > doing so enable IOMMU translations. Typically this will be before a > device driver has had a chance to either disable the display > controller or set up a new framebuffer and map it to the IOMMU. Hello Thierry, Is it always safe to enable SMMU ASID in a middle of a DMA request made by a memory client? The memory controller supports blocking DMA requests, which we are already using for the memory hot-resetting. A block could be needed before ASID is toggled. This needs to be clarified.
