From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Hans Verkuil <hans.verkuil@cisco.com>,
Tomasz Figa <tfiga@chromium.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Kyungmin Park <kyungmin.park@samsung.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Sakari Ailus <sakari.ailus@iki.fi>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Pawel Osciak <posciak@chromium.org>,
linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH 00/15] Implement V4L2_BUF_FLAG_NO_CACHE_* flags
Date: Wed, 8 Jan 2020 11:27:41 +0900 [thread overview]
Message-ID: <20200108022741.GA7366@google.com> (raw)
In-Reply-To: <20191217032034.54897-1-senozhatsky@chromium.org>
On (19/12/17 12:20), Sergey Senozhatsky wrote:
> Hello,
>
> RFC
>
> 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.
Gentle ping.
-ss
prev parent reply other threads:[~2020-01-08 2:27 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-17 3:20 [RFC][PATCH 00/15] Implement V4L2_BUF_FLAG_NO_CACHE_* flags Sergey Senozhatsky
2019-12-17 3:20 ` [RFC][PATCH 01/15] videobuf2: add cache management members Sergey Senozhatsky
2019-12-17 3:20 ` [RFC][PATCH 02/15] videobuf2: handle V4L2 buffer cache flags Sergey Senozhatsky
2020-01-10 10:24 ` Hans Verkuil
2020-01-22 1:39 ` Sergey Senozhatsky
2020-01-22 2:53 ` Sergey Senozhatsky
2020-01-28 4:35 ` Tomasz Figa
2019-12-17 3:20 ` [RFC][PATCH 03/15] videobuf2: add V4L2_FLAG_MEMORY_NON_CONSISTENT flag Sergey Senozhatsky
2020-01-10 9:36 ` Hans Verkuil
2020-01-10 9:46 ` Sergey Senozhatsky
2019-12-17 3:20 ` [RFC][PATCH 04/15] videobuf2: add queue memory consistency parameter Sergey Senozhatsky
2020-01-10 9:47 ` Hans Verkuil
2020-01-22 2:05 ` Sergey Senozhatsky
2020-01-23 11:02 ` Hans Verkuil
2020-01-24 2:04 ` Sergey Senozhatsky
2019-12-17 3:20 ` [RFC][PATCH 05/15] videobuf2: handle V4L2_FLAG_MEMORY_NON_CONSISTENT in REQBUFS Sergey Senozhatsky
2020-01-10 9:55 ` Hans Verkuil
2020-01-22 2:18 ` Sergey Senozhatsky
2020-01-22 3:48 ` Sergey Senozhatsky
2020-01-23 11:08 ` Hans Verkuil
2020-01-28 4:45 ` Tomasz Figa
2020-01-28 8:38 ` Hans Verkuil
2019-12-17 3:20 ` [RFC][PATCH 06/15] videobuf2: handle V4L2_FLAG_MEMORY_NON_CONSISTENT in CREATE_BUFS Sergey Senozhatsky
2020-01-10 9:59 ` Hans Verkuil
2020-01-23 3:41 ` Sergey Senozhatsky
2020-01-23 11:41 ` Hans Verkuil
2020-01-24 1:28 ` Sergey Senozhatsky
2019-12-17 3:20 ` [RFC][PATCH 07/15] videobuf2: factor out planes prepare/finish functions Sergey Senozhatsky
2019-12-17 3:20 ` [RFC][PATCH 08/15] videobuf2: do not sync caches when we are allowed not to Sergey Senozhatsky
2019-12-17 3:20 ` [RFC][PATCH 09/15] videobuf2: check ->synced flag in prepare() and finish() Sergey Senozhatsky
2019-12-17 3:20 ` [RFC][PATCH 10/15] videobuf2: let user-space know when driver supports cache hints Sergey Senozhatsky
2019-12-17 3:20 ` [RFC][PATCH 11/15] videobuf2: add begin/end cpu_access callbacks to dma-contig Sergey Senozhatsky
2019-12-17 3:20 ` [RFC][PATCH 12/15] videobuf2: add begin/end cpu_access callbacks to dma-sg Sergey Senozhatsky
2020-01-10 10:13 ` Hans Verkuil
2020-01-22 6:37 ` Sergey Senozhatsky
2020-01-28 4:38 ` Tomasz Figa
2020-01-28 8:36 ` Hans Verkuil
2020-01-30 11:02 ` Tomasz Figa
2020-01-30 12:18 ` Hans Verkuil
2020-02-03 10:04 ` Tomasz Figa
2020-02-04 2:50 ` Sergey Senozhatsky
2020-02-06 8:51 ` Tomasz Figa
2019-12-17 3:20 ` [RFC][PATCH 13/15] videobuf2: do not sync buffers for DMABUF queues Sergey Senozhatsky
2020-01-10 10:30 ` Hans Verkuil
2020-01-22 5:05 ` Sergey Senozhatsky
2020-01-23 11:35 ` Hans Verkuil
2020-01-24 2:25 ` Sergey Senozhatsky
2020-01-24 7:32 ` Sergey Senozhatsky
2020-01-28 7:22 ` Tomasz Figa
2020-01-28 7:34 ` Sergey Senozhatsky
2020-01-28 7:19 ` Tomasz Figa
2020-01-28 8:47 ` Hans Verkuil
2019-12-17 3:20 ` [RFC][PATCH 14/15] videobuf2: don't test db_attach in dma-contig prepare and finish Sergey Senozhatsky
2020-01-10 10:32 ` Hans Verkuil
2019-12-17 3:20 ` [RFC][PATCH 15/15] videobuf2: don't test db_attach in dma-sg " Sergey Senozhatsky
2020-01-08 2:27 ` Sergey Senozhatsky [this message]
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