Hi Rob,
this is the follow-up I promised: it fixes the two remaining map
paths that still consume struct page/sg->length of imported
sg_tables, and therefore completes the DMABUF_DEBUG=y story when
applied on top of your series [1].
Test results on x1e78100 (Snapdragon X1E78100, DMABUF_DEBUG=y,
kernel v7.3-rc4 based), which is the machine that originally
reported the UCHE translation faults and the one hardware test
environment for imports of buffers not first exported by drm/msm:
- v7.3-rc4 stock: arm-smmu UCHE translation faults during hardware
video decode in clapper/chromium (bisected to 143755bdabaa9)
- your series alone: video plays via the userspace copy fallback,
zero GPU faults, but a WARN storm from __arm_lpae_unmap()
(472 traces within a minute of video playback) - every map of a
page-less sg_table silently maps nothing, so the matching unmap
finds no PTE and WARNs. This matches your cover letter saying
the map paths are not addressed by the series. Your patch 2
("mmap imported dma-bufs via the exporter") in particular works:
a test importing a linux,cma-heap buffer via
DRM_IOCTL_PRIME_FD_TO_HANDLE and mmaps it both through the heap
fd and through msm's GEM mmap sees the same memory through both
mappings, including writes visible in both directions.
- your series + this series: zero arm-smmu faults, zero io-pgtable
WARNs, and hardware video decode displays correctly in clapper
and chromium. The GPU per-process pagetable path is exercised
with real decoder capture buffers (videobuf2-dma-contig, 2MB
frames) and maps them from their DMA addresses.
Patch 1 exports iommu_get_dma_domain(), which msm needs to look up
the dma_addr -> phys mapping of imported buffers through the msm
drm device's DMA-API domain. On platforms where the drm device is
direct mapped (like mine: ae01000.display-controller is in no
iommu_group) the lookup degenerates to the identity; on platforms
where it sits behind a translated IOMMU the translation is needed.
Happy to rebase on whatever your tree looks like - and I can rerun
the full test matrix (WARN count, fault count, kmssink scanout of
real V4L2 frames, chromium/clapper hardware decode) on any revision.
[1] <[email protected]>
Jianfeng Liu (2):
iommu: export iommu_get_dma_domain()
drm/msm: map page-less imported sg_tables from their DMA addresses
drivers/gpu/drm/msm/msm_gem_vma.c | 9 ++++
drivers/gpu/drm/msm/msm_iommu.c | 90 ++++++++++++++++++++++++++++++-
drivers/gpu/drm/msm/msm_mmu.h | 13 +++++
drivers/iommu/iommu.c | 1 +
4 files changed, 111 insertions(+), 2 deletions(-)
---
base-commit: d6882ed4e5b3970a13d721a07d2737c4831cdced
branch: msm-map-followup-v1
--
2.47.3
