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authorLinus Torvalds <torvalds@linux-foundation.org>2023-11-01 19:28:35 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2023-11-01 19:28:35 +0300
commit7d461b291e65938f15f56fe58da2303b07578a76 (patch)
tree015dd7c2f1743dd70be52787dd9aff33822bc938 /Documentation/driver-api
parent8bc9e6515183935fa0cccaf67455c439afe4982b (diff)
parent631808095a82e6b6f8410a95f8b12b8d0d38b161 (diff)
downloadlinux-7d461b291e65938f15f56fe58da2303b07578a76.tar.xz
Merge tag 'drm-next-2023-10-31-1' of git://anongit.freedesktop.org/drm/drm
Pull drm updates from Dave Airlie: "Highlights: - AMD adds some more upcoming HW platforms - Intel made Meteorlake stable and started adding Lunarlake - nouveau has a bunch of display rework in prepartion for the NVIDIA GSP firmware support - msm adds a7xx support - habanalabs has finished migration to accel subsystem Detail summary: kernel: - add initial vmemdup-user-array core: - fix platform remove() to return void - drm_file owner updated to reflect owner - move size calcs to drm buddy allocator - let GPUVM build as a module - allow variable number of run-queues in scheduler edid: - handle bad h/v sync_end in EDIDs panfrost: - add Boris as maintainer fbdev: - use fb_ops helpers more - only allow logo use from fbcon - rename fb_pgproto to pgprot_framebuffer - add HPD state to drm_connector_oob_hotplug_event - convert to fbdev i/o mem helpers i915: - Enable meteorlake by default - Early Xe2 LPD/Lunarlake display enablement - Rework subplatforms into IP version checks - GuC based TLB invalidation for Meteorlake - Display rework for future Xe driver integration - LNL FBC features - LNL display feature capability reads - update recommended fw versions for DG2+ - drop fastboot module parameter - added deviceid for Arrowlake-S - drop preproduction workarounds - don't disable preemption for resets - cleanup inlines in headers - PXP firmware loading fix - Fix sg list lengths - DSC PPS state readout/verification - Add more RPL P/U PCI IDs - Add new DG2-G12 stepping - DP enhanced framing support to state checker - Improve shared link bandwidth management - stop using GEM macros in display code - refactor related code into display code - locally enable W=1 warnings - remove PSR watchdog timers on LNL amdgpu: - RAS/FRU EEPROM updatse - IP discovery updatses - GC 11.5 support - DCN 3.5 support - VPE 6.1 support - NBIO 7.11 support - DML2 support - lots of IP updates - use flexible arrays for bo list handling - W=1 fixes - Enable seamless boot in more cases - Enable context type property for HDMI - Rework GPUVM TLB flushing - VCN IB start/size alignment fixes amdkfd: - GC 10/11 fixes - GC 11.5 support - use partial migration in GPU faults radeon: - W=1 Fixes - fix some possible buffer overflow/NULL derefs nouveau: - update uapi for NO_PREFETCH - scheduler/fence fixes - rework suspend/resume for GSP-RM - rework display in preparation for GSP-RM habanalabs: - uapi: expose tsc clock - uapi: block access to eventfd through control device - uapi: force dma-buf export to PAGE_SIZE alignments - complete move to accel subsystem - move firmware interface include files - perform hard reset on PCIe AXI drain event - optimise user interrupt handling msm: - DP: use existing helpers for DPCD - DPU: interrupts reworked - gpu: a7xx (a730/a740) support - decouple msm_drv from kms for headless devices mediatek: - MT8188 dsi/dp/edp support - DDP GAMMA - 12 bit LUT support - connector dynamic selection capability rockchip: - rv1126 mipi-dsi/vop support - add planar formats ast: - rename constants panels: - Mitsubishi AA084XE01 - JDI LPM102A188A - LTK050H3148W-CTA6 ivpu: - power management fixes qaic: - add detach slice bo api komeda: - add NV12 writeback tegra: - support NVSYNC/NHSYNC - host1x suspend fixes ili9882t: - separate into own driver" * tag 'drm-next-2023-10-31-1' of git://anongit.freedesktop.org/drm/drm: (1803 commits) drm/amdgpu: Remove unused variables from amdgpu_show_fdinfo drm/amdgpu: Remove duplicate fdinfo fields drm/amd/amdgpu: avoid to disable gfxhub interrupt when driver is unloaded drm/amdgpu: Add EXT_COHERENT support for APU and NUMA systems drm/amdgpu: Retrieve CE count from ce_count_lo_chip in EccInfo table drm/amdgpu: Identify data parity error corrected in replay mode drm/amdgpu: Fix typo in IP discovery parsing drm/amd/display: fix S/G display enablement drm/amdxcp: fix amdxcp unloads incompletely drm/amd/amdgpu: fix the GPU power print error in pm info drm/amdgpu: Use pcie domain of xcc acpi objects drm/amd: check num of link levels when update pcie param drm/amdgpu: Add a read to GFX v9.4.3 ring test drm/amd/pm: call smu_cmn_get_smc_version in is_mode1_reset_supported. drm/amdgpu: get RAS poison status from DF v4_6_2 drm/amdgpu: Use discovery table's subrevision drm/amd/display: 3.2.256 drm/amd/display: add interface to query SubVP status drm/amd/display: Read before writing Backlight Mode Set Register drm/amd/display: Disable SYMCLK32_SE RCO on DCN314 ...
Diffstat (limited to 'Documentation/driver-api')
-rw-r--r--Documentation/driver-api/dma-buf.rst32
1 files changed, 24 insertions, 8 deletions
diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst
index f92a32d095d9..0c153d79ccc4 100644
--- a/Documentation/driver-api/dma-buf.rst
+++ b/Documentation/driver-api/dma-buf.rst
@@ -5,14 +5,30 @@ The dma-buf subsystem provides the framework for sharing buffers for
hardware (DMA) access across multiple device drivers and subsystems, and
for synchronizing asynchronous hardware access.
-This is used, for example, by drm "prime" multi-GPU support, but is of
-course not limited to GPU use cases.
-
-The three main components of this are: (1) dma-buf, representing a
-sg_table and exposed to userspace as a file descriptor to allow passing
-between devices, (2) fence, which provides a mechanism to signal when
-one device has finished access, and (3) reservation, which manages the
-shared or exclusive fence(s) associated with the buffer.
+As an example, it is used extensively by the DRM subsystem to exchange
+buffers between processes, contexts, library APIs within the same
+process, and also to exchange buffers with other subsystems such as
+V4L2.
+
+This document describes the way in which kernel subsystems can use and
+interact with the three main primitives offered by dma-buf:
+
+ - dma-buf, representing a sg_table and exposed to userspace as a file
+ descriptor to allow passing between processes, subsystems, devices,
+ etc;
+ - dma-fence, providing a mechanism to signal when an asynchronous
+ hardware operation has completed; and
+ - dma-resv, which manages a set of dma-fences for a particular dma-buf
+ allowing implicit (kernel-ordered) synchronization of work to
+ preserve the illusion of coherent access
+
+
+Userspace API principles and use
+--------------------------------
+
+For more details on how to design your subsystem's API for dma-buf use, please
+see Documentation/userspace-api/dma-buf-alloc-exchange.rst.
+
Shared DMA Buffers
------------------