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?

Robin.


[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/580804.html
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-December/474443.html

Robin Murphy (4):
  dma-mapping: Generalise dma_32bit_limit flag
  ACPI/IORT: Set bus DMA mask as appropriate
  of/device: Set bus DMA mask as appropriate
  iommu/dma: Respect bus DMA limit for IOVAs

 arch/x86/kernel/pci-dma.c | 2 +-
 drivers/acpi/arm64/iort.c | 1 +
 drivers/iommu/dma-iommu.c | 3 +++
 drivers/of/device.c       | 1 +
 include/linux/device.h    | 6 +++---
 kernel/dma/direct.c       | 2 +-
 6 files changed, 10 insertions(+), 5 deletions(-)

-- 
2.17.1.dirty

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