On Wed, Nov 06, 2024 at 10:10:08PM +0100, Janne Grunau via B4 Relay wrote:
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...
Sorry for the late reply here, can you please rebase on top of current master? A few other changes / clean-ups have gone in and I can't easily rebase and confirm the changes right now. Thanks!