The changes in "Make LMB memory map global and persistent" [1] break mapping DMA memory in the USB xHCI driver when using the apple_dart iommu present on Apple silicon systems.
The IOVA space used by the u-boot driver (low 4GB) and physical memory do not overlap. The physical memory on this systems starts depending on the SoC either at 0x10_0000_0000 or 0x100_0000_0000. It make no sense to manage these distinct regions in a single LMB map. In addition every device has its own iommu and IO address space so sharing a single memory map between all iommu instances is not necessary.
To fix this issue restore the used subset (add, alloc and free) of the previous pointer based LMB interface with "io_" as prefix.
To ensure that low level lmb functions do not use the global LMB variable reorder lib/lmb.c so that the variable is not visible.
Tested with patches from my "Fix device removal order for Apple dart iommu" series [2] to fix a separate issue.
The cosmetic commit has two checkpatch warnings in existing code which I ignored.
[1] https://lore.kernel.org/u-boot/20240826115940.3233167-1-sughosh.ganu@linaro.... [2] https://lore.kernel.org/u-boot/20241031-iommu_apple_dart_ordering-v1-0-8a687...
Signed-off-by: Janne Grunau j@jannau.net --- Changes in v2: - added io_lmb_teardown() and use it in dart's remove callback - removed leftover from copy-n-paste in io_lmb_setup() documentation - added Tom's Rb: - Link to v1: https://lore.kernel.org/r/20241101-io_lmb_apple_dart_iommu-v1-0-fe4b9a74d47c...
--- Janne Grunau (4): lmb: Do not use global LMB variable in _lmb_free() lmb: cosmetic: reorder functions and global LMB variable lmb: Add basic io_lmb functionality iommu: apple: Manage IOVA separately from global LMB mem map
drivers/iommu/apple_dart.c | 18 +- include/lmb.h | 51 ++++ lib/lmb.c | 614 ++++++++++++++++++++++++++------------------- 3 files changed, 418 insertions(+), 265 deletions(-) --- base-commit: 1d147b74f437fb0e85821e8271fe52bc5fd30194 change-id: 20241101-io_lmb_apple_dart_iommu-dc2674ef9036
Best regards,