Hello, v5 with fixes and improvements. I have a simple v4l-compliance patch now (will send it separately) which tests cache and consistency hints. I ran compliance against the vivid test driver, which was additionally extended with cache_hints module param: Trimmed v4l-compliance output: - vivid with disabled cache hints support [..] Buffer ioctls (Input 3): test V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS: OK test V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS: OK test V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS: OK test VIDIOC_REQBUFS/CREATE_BUFS/QUERYBUF: OK test VIDIOC_EXPBUF: OK [..] - vivid with enabled cache hints (cache_hints=1,...) [..] Buffer ioctls (Input 3): test V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS: OK test V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS: OK test V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS: OK test VIDIOC_REQBUFS/CREATE_BUFS/QUERYBUF: OK test VIDIOC_EXPBUF: OK [..] v4l-compliance revealed that we cannot reliably report V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS, it's a bit special. Let's look at fill_buf_caps() if (q->allow_cache_hints && q->io_modes & VB2_MMAP) *caps |= V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS; There are several things here. First, if the queue is not setup yet (we didn't call driver's ->queue_setup()) then ->allow_cache_hints is expected to be 0. It's only in the ->queue_setup() that the driver sets ->allow_cache_hints for those queues that can benefit from cache management. What this means, is that if one does q.init(node->g_type(), memory); q.reqbufs(node); q.g_capabilities(); the cache hints cap will not be reported. We need to setup the queue q.init(node->g_type(), memory); q.reqbufs(node, 1); q.g_capabilities(); Second. Even if the queue is setup, we still can report wrong cache hint values. Let's look at the following code fill_buf_caps(q, &p->capabilities); if (!vb2_queue_allows_cache_hints(q)) p->flags &= ~V4L2_FLAG_MEMORY_NON_CONSISTENT; ret = vb2_core_reqbufs(...); return ret; The thing here is that vb2_core_reqbufs() and vb2_core_create_bufs() can re-initialize the queue and invoke ->queue_setup(), possibly changing its memory model, etc. so cache hints cap which we set or clear before vb2_core_reqbufs() and vb2_core_create_bufs() can become invalid after we call those functions. It's the same with ``req->flags &= ~V4L2_FLAG_MEMORY_NON_CONSISTENT``, we cannot clear it before reqbufs()/create_bufs(). Therefore I added two simple functions which fixup cache hint cap and non_consistent flag after reqbufs()/create_bufs(). So the code looks like this now: fill_buf_caps(q, &p->capabilities); ret = vb2_core_reqbufs(...); fixup_consistency_attr(q, &p->flags); fixup_cache_hints_cap(q, &p->capabilities); return ret; The rest is the pretty much the same. Previous series: v4 link: https://lore.kernel.org/lkml/20200302041213.27662-1-senozhatsky@xxxxxxxxxxxx/ v3 link: https://lore.kernel.org/lkml/20200226111529.180197-1-senozhatsky@xxxxxxxxxxxx v2 link: https://lore.kernel.org/lkml/20200204025641.218376-1-senozhatsky@xxxxxxxxxxxx/ v1 link: https://lore.kernel.org/lkml/20191217032034.54897-1-senozhatsky@xxxxxxxxxxxx/ Series Intro ======================================================================== This is a reworked version of the vb2 cache hints (V4L2_BUF_FLAG_NO_CACHE_INVALIDATE / V4L2_BUF_FLAG_NO_CACHE_CLEAN) support patch series which previsouly was developed by Sakari and Laurent [0]. The patch set attempts to preserve the existing behvaiour - cache sync is performed in ->prepare() and ->finish() (unless the buffer is DMA exported). User space can request “default behavior” override with cache management hints, which are handled on a per-buffer basis and should be supplied with v4l2_buffer ->flags during buffer preparation. There are two possible hints: - V4L2_BUF_FLAG_NO_CACHE_INVALIDATE No cache sync on ->finish() - V4L2_BUF_FLAG_NO_CACHE_CLEAN No cache sync on ->prepare() In order to keep things on the safe side, we also require driver to explicitly state which of its queues (if any) support user space cache management hints (such queues should have ->allow_cache_hints bit set). The patch set also (to some extent) simplifies allocators' ->prepare() and ->finish() callbacks. Namely, we move cache management decision making to the upper - core - layer. For example, if, previously, we would have something like this vb2_buffer_done() vb2_dc_finish() if (buf->db_attach) return; where each allocators' ->finish() callback would either bail out (DMA exported buffer, for instance) or sync, now that "bail out or sync" decision is made before we call into the allocator. Along with cache management hints, user space is also able to adjust queue's memory consistency attributes. Memory consistency attribute (dma_attrs) is per-queue, yet it plays its role on the allocator level, when we allocate buffers’ private memory (planes). For the time being, only one consistency attribute is supported: DMA_ATTR_NON_CONSISTENT. [0] https://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg112459.html Sergey Senozhatsky (13): videobuf2: use explicit unsigned int in vb2_queue videobuf2: add cache management members videobuf2: handle V4L2 buffer cache flags videobuf2: add V4L2_FLAG_MEMORY_NON_CONSISTENT flag videobuf2: add queue memory consistency parameter videobuf2: handle V4L2_FLAG_MEMORY_NON_CONSISTENT flag videobuf2: factor out planes prepare/finish functions videobuf2: do not sync caches when we are allowed not to videobuf2: check ->synced flag in prepare() and finish() videobuf2: add begin/end cpu_access callbacks to dma-contig videobuf2: add begin/end cpu_access callbacks to dma-sg videobuf2: don't test db_attach in dma-contig prepare and finish media: vivid: add cache_hints module param Documentation/admin-guide/media/vivid.rst | 9 ++ .../userspace-api/media/v4l/buffer.rst | 41 +++++- .../media/v4l/vidioc-create-bufs.rst | 7 +- .../media/v4l/vidioc-reqbufs.rst | 20 ++- .../media/common/videobuf2/videobuf2-core.c | 121 +++++++++++++----- .../common/videobuf2/videobuf2-dma-contig.c | 41 +++++- .../media/common/videobuf2/videobuf2-dma-sg.c | 38 ++++-- .../media/common/videobuf2/videobuf2-v4l2.c | 93 +++++++++++++- drivers/media/dvb-core/dvb_vb2.c | 2 +- drivers/media/test-drivers/vivid/vivid-core.c | 9 ++ drivers/media/test-drivers/vivid/vivid-core.h | 1 + .../media/test-drivers/vivid/vivid-meta-cap.c | 5 + .../media/test-drivers/vivid/vivid-meta-out.c | 5 + .../media/test-drivers/vivid/vivid-sdr-cap.c | 7 + .../test-drivers/vivid/vivid-touch-cap.c | 5 + .../media/test-drivers/vivid/vivid-vbi-cap.c | 5 + .../media/test-drivers/vivid/vivid-vbi-out.c | 5 + .../media/test-drivers/vivid/vivid-vid-cap.c | 5 + .../media/test-drivers/vivid/vivid-vid-out.c | 5 + drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 9 +- drivers/media/v4l2-core/v4l2-ioctl.c | 5 +- include/media/videobuf2-core.h | 47 +++++-- include/uapi/linux/videodev2.h | 13 +- 23 files changed, 426 insertions(+), 72 deletions(-) -- 2.26.2
