pm24.git/Documentation/driver-api/dma-buf.rst, branch v6.5

dma-buf/sync_file: Surface sync-file uABI

2023-03-28T20:39:02Z

We had all of the internal driver APIs, but not the all important userspace uABI, in the dma-buf doc. Fix that. And re-arrange the comments slightly as otherwise the comments for the ioctl nr defines would not show up. v2: Fix docs build warning coming from newly including the uabi header in the docs build Signed-off-by: Rob Clark Acked-by: Pekka Paalanen

dma-buf/dma-fence: Add deadline awareness

2023-03-25T17:55:07Z

Add a way to hint to the fence signaler of an upcoming deadline, such as vblank, which the fence waiter would prefer not to miss. This is to aid the fence signaler in making power management decisions, like boosting frequency as the deadline approaches and awareness of missing deadlines so that can be factored in to the frequency scaling. v2: Drop dma_fence::deadline and related logic to filter duplicate deadlines, to avoid increasing dma_fence size. The fence-context implementation will need similar logic to track deadlines of all the fences on the same timeline. [ckoenig] v3: Clarify locking wrt. set_deadline callback v4: Clarify in docs comment that this is a hint v5: Drop DMA_FENCE_FLAG_HAS_DEADLINE_BIT. v6: More docs v7: Fix typo, clarify past deadlines Signed-off-by: Rob Clark Reviewed-by: Christian König Acked-by: Pekka Paalanen Reviewed-by: Bagas Sanjaya

Documentation: driver-api: correct spelling

2023-02-02T18:05:16Z

Correct spelling problems for Documentation/driver-api/ as reported by codespell. Signed-off-by: Randy Dunlap Cc: Mauro Carvalho Chehab Cc: linux-media@vger.kernel.org Cc: Vishal Verma Cc: Dave Jiang Cc: nvdimm@lists.linux.dev Cc: Vinod Koul Cc: dmaengine@vger.kernel.org Cc: linux-raid@vger.kernel.org Cc: linux-usb@vger.kernel.org Acked-by: Dan Williams Acked-by: Song Liu Acked-by: Greg Kroah-Hartman Link: https://lore.kernel.org/r/20230129231053.20863-3-rdunlap@infradead.org Signed-off-by: Jonathan Corbet

dma-buf: Add "dma-buf" to title of documentation

2023-01-31T20:56:05Z

To make it easier to find the dma-buf documentation when looking through tables-of-contents etc., put the name "dma-buf" in the title. Signed-off-by: Jonathan Neuschäfer Link: https://lore.kernel.org/r/20230129115917.1229529-1-j.neuschaefer@gmx.net Signed-off-by: Jonathan Corbet

dma-buf: Document dynamic locking convention

2022-10-17T22:21:53Z

Add documentation for the dynamic locking convention. The documentation tells dma-buf API users when they should take the reservation lock and when not. Acked-by: Sumit Semwal Reviewed-by: Christian König Signed-off-by: Dmitry Osipenko Link: https://patchwork.freedesktop.org/patch/msgid/20221017172229.42269-20-dmitry.osipenko@collabora.com

dma-buf: add dma_fence_unwrap v2

2022-03-25T13:18:28Z

Add a general purpose helper to deep dive into dma_fence_chain/dma_fence_array structures and iterate over all the fences in them. This is useful when we need to flatten out all fences in those structures. v2: some selftests cleanup, improved function naming and documentation Signed-off-by: Christian König Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220311110244.1245-1-christian.koenig@amd.com

dma-buf-map: Rename to iosys-map

2022-02-08T00:35:35Z

Rename struct dma_buf_map to struct iosys_map and corresponding APIs. Over time dma-buf-map grew up to more functionality than the one used by dma-buf: in fact it's just a shim layer to abstract system memory, that can be accessed via regular load and store, from IO memory that needs to be acessed via arch helpers. The idea is to extend this API so it can fulfill other needs, internal to a single driver. Example: in the i915 driver it's desired to share the implementation for integrated graphics, which uses mostly system memory, with discrete graphics, which may need to access IO memory. The conversion was mostly done with the following semantic patch: @r1@ @@ - struct dma_buf_map + struct iosys_map @r2@ @@ ( - DMA_BUF_MAP_INIT_VADDR + IOSYS_MAP_INIT_VADDR | - dma_buf_map_set_vaddr + iosys_map_set_vaddr | - dma_buf_map_set_vaddr_iomem + iosys_map_set_vaddr_iomem | - dma_buf_map_is_equal + iosys_map_is_equal | - dma_buf_map_is_null + iosys_map_is_null | - dma_buf_map_is_set + iosys_map_is_set | - dma_buf_map_clear + iosys_map_clear | - dma_buf_map_memcpy_to + iosys_map_memcpy_to | - dma_buf_map_incr + iosys_map_incr ) @@ @@ - #include + #include Then some files had their includes adjusted and some comments were update to remove mentions to dma-buf-map. Since this is not specific to dma-buf anymore, move the documentation to the "Bus-Independent Device Accesses" section. v2: - Squash patches v3: - Fix wrong removal of dma-buf.h from MAINTAINERS - Move documentation from dma-buf.rst to device-io.rst v4: - Change documentation title and level Signed-off-by: Lucas De Marchi Acked-by: Christian König Acked-by: Sumit Semwal Acked-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20220204170541.829227-1-lucas.demarchi@intel.com

dma-buf: cleanup kerneldoc of removed component

2021-09-02T11:14:40Z

The seqno-fence was removed, cleanup the kerneldoc include as well. Signed-off-by: Christian König Acked-by: Sumit Semwal Fixes: 992c238188a8 ("dma-buf: nuke seqno-fence") Link: https://patchwork.freedesktop.org/patch/msgid/20210901080002.5892-1-christian.koenig@amd.com

dma-buf: Document DMA_BUF_IOCTL_SYNC (v3)

2021-06-17T19:46:37Z

This adds a new "DMA Buffer ioctls" section to the dma-buf docs and adds documentation for DMA_BUF_IOCTL_SYNC. v2 (Daniel Vetter): - Fix a couple typos - Add commentary about synchronization with other devices - Use item list format for describing flags v3 (Pekka Paalanen): - Clarify stalling requirements. - Be more clear that that DMA_BUF_IOCTL_SYNC with SINC_END has to be called before more GPU work happens. Signed-off-by: Jason Ekstrand Reviewed-by: Daniel Vetter Acked-by: Christian König Acked-by: Pekka Paalanen Cc: Sumit Semwal Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20210617194258.579011-1-jason@jlekstrand.net

dmabuf: Add the capability to expose DMA-BUF stats in sysfs

2021-06-15T09:50:24Z

Overview ======== The patch adds DMA-BUF statistics to /sys/kernel/dmabuf/buffers. It allows statistics to be enabled for each DMA-BUF in sysfs by enabling the config CONFIG_DMABUF_SYSFS_STATS. The following stats will be exposed by the interface: /sys/kernel/dmabuf/buffers//exporter_name /sys/kernel/dmabuf/buffers//size /sys/kernel/dmabuf/buffers//attachments//device /sys/kernel/dmabuf/buffers//attachments//map_counter The inode_number is unique for each DMA-BUF and was added earlier [1] in order to allow userspace to track DMA-BUF usage across different processes. Use Cases ========= The interface provides a way to gather DMA-BUF per-buffer statistics from production devices. These statistics will be used to derive DMA-BUF per-exporter stats and per-device usage stats for Android Bug reports. The corresponding userspace changes can be found at [2]. Telemetry tools will also capture this information(along with other memory metrics) periodically as well as on important events like a foreground app kill (which might have been triggered by Low Memory Killer). It will also contribute to provide a snapshot of the system memory usage on other events such as OOM kills and Application Not Responding events. Background ========== Currently, there are two existing interfaces that provide information about DMA-BUFs. 1) /sys/kernel/debug/dma_buf/bufinfo debugfs is however unsuitable to be mounted in production systems and cannot be considered as an alternative to the sysfs interface being proposed. 2) proc//fdinfo/ The proc//fdinfo/ files expose information about DMA-BUF fds. However, the existing procfs interfaces can only provide information about the buffers for which processes hold fds or have the buffers mmapped into their address space. Since the procfs interfaces alone cannot provide a full picture of all DMA-BUFs in the system, there is the need for an alternate interface to provide this information on production systems. The patch contains the following major improvements over v1: 1) Each attachment is represented by its own directory to allow creating a symlink to the importing device and to also provide room for future expansion. 2) The number of distinct mappings of each attachment is exposed in a separate file. 3) The per-buffer statistics are now in /sys/kernel/dmabuf/buffers inorder to make the interface expandable in future. All of the improvements above are based on suggestions/feedback from Daniel Vetter and Christian König. A shell script that can be run on a classic Linux environment to read out the DMA-BUF statistics can be found at [3](suggested by John Stultz). [1]: https://lore.kernel.org/patchwork/patch/1088791/ [2]: https://android-review.googlesource.com/q/topic:%22dmabuf-sysfs%22+(status:open%20OR%20status:merged) [3]: https://android-review.googlesource.com/c/platform/system/memory/libmeminfo/+/1549734 Reviewed-by: Greg Kroah-Hartman Signed-off-by: Hridya Valsaraju Reported-by: kernel test robot Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20210603214758.2955251-1-hridya@google.com