From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: 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>
Cc: 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,
Sergey Senozhatsky <senozhatsky@chromium.org>
Subject: [RFC][PATCHv2 03/12] videobuf2: add V4L2_FLAG_MEMORY_NON_CONSISTENT flag
Date: Tue, 4 Feb 2020 11:56:32 +0900 [thread overview]
Message-ID: <20200204025641.218376-4-senozhatsky@chromium.org> (raw)
In-Reply-To: <20200204025641.218376-1-senozhatsky@chromium.org>
By setting or clearing V4L2_FLAG_MEMORY_NON_CONSISTENT flag
user-space should be able to set or clear queue's NON_CONSISTENT
->dma_attrs. Queue's ->dma_attrs are passed to the underlying
allocator in __vb2_buf_mem_alloc(), so thus user-space is able
to request vb2 buffer's memory to be either consistent (coherent)
or non-consistent.
Change-Id: Ib333081c482e23c9a89386078293e19c3fd59076
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
Documentation/media/uapi/v4l/buffer.rst | 27 +++++++++++++++++++++++++
include/uapi/linux/videodev2.h | 2 ++
2 files changed, 29 insertions(+)
diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst
index 9149b57728e5..af007daf0591 100644
--- a/Documentation/media/uapi/v4l/buffer.rst
+++ b/Documentation/media/uapi/v4l/buffer.rst
@@ -705,6 +705,33 @@ Buffer Flags
.. c:type:: v4l2_memory
+Memory Consistency Flags
+========================
+
+.. tabularcolumns:: |p{7.0cm}|p{2.2cm}|p{8.3cm}|
+
+.. cssclass:: longtable
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 3 1 4
+
+ * .. _`V4L2_FLAG_MEMORY_NON_CONSISTENT`:
+
+ - ``V4L2_FLAG_MEMORY_NON_CONSISTENT``
+ - 0x00000001
+ - vb2 buffer is allocated either in consistent (it will be automatically
+ coherent between CPU and bus) or non-consistent memory. The latter
+ can provide performance gains, for instance CPU cache sync/flush
+ operations can be avoided if the buffer is accesed by the corresponding
+ device only and CPU does not read/write to/from that buffer. However,
+ this requires extra care from the driver -- it must guarantee memory
+ consistency by issuing cache flush/sync when consistency is needed.
+ If this flag is set V4L2 will attempt to allocate vb2 buffer in
+ non-consistent memory. This flag is ignored if queue does not report
+ :ret:`V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS` capability.
+
enum v4l2_memory
================
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 5f9357dcb060..72efc1c544cd 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -189,6 +189,8 @@ enum v4l2_memory {
V4L2_MEMORY_DMABUF = 4,
};
+#define V4L2_FLAG_MEMORY_NON_CONSISTENT (1 << 0)
+
/* see also http://vektor.theorem.ca/graphics/ycbcr/ */
enum v4l2_colorspace {
/*
--
2.25.0.341.g760bfbb309-goog
next prev parent reply other threads:[~2020-02-04 2:57 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-04 2:56 [RFC][PATCHv2 00/12] Implement V4L2_BUF_FLAG_NO_CACHE_* flags Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 01/12] videobuf2: add cache management members Sergey Senozhatsky
2020-02-19 8:05 ` Hans Verkuil
2020-02-19 8:16 ` Sergey Senozhatsky
2020-02-19 8:27 ` Hans Verkuil
2020-02-04 2:56 ` [RFC][PATCHv2 02/12] videobuf2: handle V4L2 buffer cache flags Sergey Senozhatsky
2020-02-05 8:13 ` Sergey Senozhatsky
2020-02-19 8:07 ` Hans Verkuil
2020-02-19 8:13 ` Sergey Senozhatsky
2020-02-19 8:25 ` Hans Verkuil
2020-02-19 8:46 ` Hans Verkuil
2020-02-04 2:56 ` Sergey Senozhatsky [this message]
2020-02-13 7:08 ` [RFC][PATCHv2 03/12] videobuf2: add V4L2_FLAG_MEMORY_NON_CONSISTENT flag Tomasz Figa
2020-02-19 8:19 ` Hans Verkuil
2020-02-19 8:56 ` Hans Verkuil
2020-02-25 7:45 ` Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 04/12] videobuf2: add queue memory consistency parameter Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 05/12] videobuf2: handle V4L2_FLAG_MEMORY_NON_CONSISTENT flag Sergey Senozhatsky
2020-02-19 8:25 ` Hans Verkuil
2020-02-19 8:59 ` Sergey Senozhatsky
2020-02-19 9:04 ` Hans Verkuil
2020-02-19 8:48 ` Hans Verkuil
2020-02-19 9:05 ` Sergey Senozhatsky
2020-02-19 9:11 ` Hans Verkuil
2020-02-04 2:56 ` [RFC][PATCHv2 06/12] videobuf2: factor out planes prepare/finish functions Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 07/12] videobuf2: do not sync caches when we are allowed not to Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 08/12] videobuf2: check ->synced flag in prepare() and finish() Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 09/12] videobuf2: let user-space know if driver supports cache hints Sergey Senozhatsky
2020-02-19 8:33 ` Hans Verkuil
2020-02-19 8:45 ` Sergey Senozhatsky
2020-02-19 8:56 ` Hans Verkuil
2020-02-04 2:56 ` [RFC][PATCHv2 10/12] videobuf2: add begin/end cpu_access callbacks to dma-contig Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 11/12] videobuf2: add begin/end cpu_access callbacks to dma-sg Sergey Senozhatsky
2020-02-19 8:35 ` Hans Verkuil
2020-02-19 8:42 ` Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 12/12] videobuf2: don't test db_attach in dma-contig prepare and finish Sergey Senozhatsky
2020-02-19 8:53 ` [RFC][PATCHv2 00/12] Implement V4L2_BUF_FLAG_NO_CACHE_* flags Hans Verkuil
2020-02-26 11:20 ` Sergey Senozhatsky
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200204025641.218376-4-senozhatsky@chromium.org \
--to=senozhatsky@chromium.org \
--cc=hans.verkuil@cisco.com \
--cc=kyungmin.park@samsung.com \
--cc=laurent.pinchart@ideasonboard.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=m.szyprowski@samsung.com \
--cc=mchehab@kernel.org \
--cc=posciak@chromium.org \
--cc=sakari.ailus@iki.fi \
--cc=tfiga@chromium.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).