v2: Send the two related patches together as a series, as requested by Jani. No code changes from v1.
This series fixes two related issues in MST payload bandwidth accounting that together caused 4K@60Hz to fail alongside two 1080p@60Hz displays in a 3-display MST daisy-chain topology (PS8650 hub -> ViewSonic VP2468 x2 -> Lenovo Pro 27UD-10). Patch 1 fixes the PBN value passed in the ALLOCATE_PAYLOAD sideband request. The driver was using a TU-aligned PBN (e.g. 537) instead of the actual video stream bandwidth (e.g. 496 for [email protected]), inflating the requested PBN and causing -ENOSPC failures for configurations that should fit within the available link bandwidth. Patch 2 tracks the allocated_pbn returned in the ALLOCATE_PAYLOAD reply, and uses it alongside @pbn for bandwidth limit checks. This ensures that any per-hop capacity constraints from intermediate MST branches are correctly reflected in the source-side bandwidth check. Xiao Lu (2): drm/i915/dp: fix PBN in ALLOCATE_PAYLOAD request to use actual video bandwidth drm/dp/mst: track allocated_pbn from ALLOCATE_PAYLOAD reply drivers/gpu/drm/display/drm_dp_mst_topology.c | 24 ++++++++++++++---- drivers/gpu/drm/i915/display/intel_dp_mst.c | 24 +++++++++++------ include/drm/display/drm_dp_mst_helper.h | 10 +++++++ 3 files changed, 46 insertions(+), 12 deletions(-) -- 2.43.0
