These patches attempt to deal with this in the simplest way possible by
generalising the specific quirk for 32-bit bridges into an arbitrary
mask which can then also be plumbed into the firmware code. In the
interest of being minimally invasive, I've only included a point fix
for the IOMMU issue as seen on arm64 - there may be further tweaks
needed in DMA ops to catch all possible incarnations of this problem,
but this initial RFC is mostly about the impact beyond the dma-mapping
subsystem itself.
Thanks, this looks very nice to me.
In fact it probably solves the RISC-V/Xiling problem as well if we can
just add the dma-ranges property to the device tree for the affected
systems. Palmer, do you know how easily the DT could be updated for
that case?