Lines Matching full:dma
4 The dma-buf subsystem provides the framework for sharing buffers for
5 hardware (DMA) access across multiple device drivers and subsystems, and
11 The three main components of this are: (1) dma-buf, representing a
17 Shared DMA Buffers
20 This document serves as a guide to device-driver writers on what is the dma-buf
23 Any device driver which wishes to be a part of DMA buffer sharing, can do so as
49 Any exporters or users of the dma-buf buffer sharing framework must have a
55 Mostly a DMA buffer file descriptor is simply an opaque object for userspace,
59 - Since kernel 3.12 the dma-buf FD supports the llseek system call, but only
64 If llseek on dma-buf FDs isn't support the kernel will report -ESPIPE for all
65 cases. Userspace can use this to detect support for discovering the dma-buf
81 flag be set when the dma-buf fd is created. So any API provided by
85 - Memory mapping the contents of the DMA buffer is also supported. See the
86 discussion below on `CPU Access to DMA Buffer Objects`_ for the full details.
88 - The DMA buffer FD is also pollable, see `Implicit Fence Poll Support`_ below for
91 - The DMA buffer FD also supports a few dma-buf-specific ioctls, see
92 `DMA Buffer ioctls`_ below for details.
94 Basic Operation and Device DMA Access
97 .. kernel-doc:: drivers/dma-buf/dma-buf.c
98 :doc: dma buf device access
100 CPU Access to DMA Buffer Objects
103 .. kernel-doc:: drivers/dma-buf/dma-buf.c
109 .. kernel-doc:: drivers/dma-buf/dma-buf.c
112 DMA-BUF statistics
114 .. kernel-doc:: drivers/dma-buf/dma-buf-sysfs-stats.c
117 DMA Buffer ioctls
120 .. kernel-doc:: include/uapi/linux/dma-buf.h
125 .. kernel-doc:: drivers/dma-buf/dma-buf.c
128 .. kernel-doc:: include/linux/dma-buf.h
134 .. kernel-doc:: drivers/dma-buf/dma-resv.c
137 .. kernel-doc:: drivers/dma-buf/dma-resv.c
140 .. kernel-doc:: include/linux/dma-resv.h
143 DMA Fences
146 .. kernel-doc:: drivers/dma-buf/dma-fence.c
147 :doc: DMA fences overview
149 DMA Fence Cross-Driver Contract
152 .. kernel-doc:: drivers/dma-buf/dma-fence.c
155 DMA Fence Signalling Annotations
158 .. kernel-doc:: drivers/dma-buf/dma-fence.c
161 DMA Fences Functions Reference
164 .. kernel-doc:: drivers/dma-buf/dma-fence.c
167 .. kernel-doc:: include/linux/dma-fence.h
170 DMA Fence Array
173 .. kernel-doc:: drivers/dma-buf/dma-fence-array.c
176 .. kernel-doc:: include/linux/dma-fence-array.h
179 DMA Fence Chain
182 .. kernel-doc:: drivers/dma-buf/dma-fence-chain.c
185 .. kernel-doc:: include/linux/dma-fence-chain.h
188 DMA Fence unwrap
191 .. kernel-doc:: include/linux/dma-fence-unwrap.h
194 DMA Fence uABI/Sync File
197 .. kernel-doc:: drivers/dma-buf/sync_file.c
203 Indefinite DMA Fences
218 are then imported as a DMA fence for integration into existing winsys
222 batch DMA fences for memory management instead of context preemption DMA
227 in-kernel DMA fences does not work, even when a fallback timeout is included to
230 * Only the kernel knows about all DMA fence dependencies, userspace is not aware
238 dependent upon DMA fences. If the kernel also support indefinite fences in the
239 kernel like a DMA fence, like any of the above proposal would, there is the
248 kernel [label="Kernel DMA Fences"]
266 * No future fences, proxy fences or userspace fences imported as DMA fences,
269 * No DMA fences that signal end of batchbuffer for command submission where
278 implications for DMA fences.
282 But memory allocations are not allowed to gate completion of DMA fences, which
283 means any workload using recoverable page faults cannot use DMA fences for
288 Linux rely on DMA fences, which means without an entirely new userspace stack
297 job with a DMA fence and a compute workload using recoverable page faults are
304 allocation is waiting for the DMA fence of the 3D workload to complete.
312 - DMA fence workloads and workloads which need page fault handling have
315 reservations for DMA fence workloads.
318 hardware resources for DMA fence workloads when they are in-flight. This must
319 cover the time from when the DMA fence is visible to other threads up to
324 requiring DMA fences or jobs requiring page fault handling: This means all DMA
326 inserted into the scheduler queue. And vice versa, before a DMA fence can be
332 memory blocks or runtime tracking of the full dependency graph of all DMA
339 GPUs do not have any impact. This allows us to keep using DMA fences internally
343 In some ways this page fault problem is a special case of the `Infinite DMA
345 depend on DMA fences, but not the other way around. And not even the page fault