From: Hans Verkuil <hverkuil@xs4all.nl>
To: Sakari Ailus <sakari.ailus@iki.fi>, linux-media@vger.kernel.org
Cc: laurent.pinchart@ideasonboard.com, k.debski@samsung.com
Subject: Re: [PATCH v5.2 3/7] v4l: Add timestamp source flags, mask and document them
Date: Sun, 23 Feb 2014 12:36:09 +0100 [thread overview]
Message-ID: <5309DD29.5060003@xs4all.nl> (raw)
In-Reply-To: <1393152034-21336-1-git-send-email-sakari.ailus@iki.fi>
On 02/23/2014 11:40 AM, Sakari Ailus wrote:
> Some devices do not produce timestamps that correspond to the end of the
> frame. The user space should be informed on the matter. This patch achieves
> that by adding buffer flags (and a mask) for timestamp sources since more
> possible timestamping points are expected than just two.
>
> A three-bit mask is defined (V4L2_BUF_FLAG_TSTAMP_SRC_MASK) and two of the
> eight possible values is are defined V4L2_BUF_FLAG_TSTAMP_SRC_EOF for end of
> frame (value zero) V4L2_BUF_FLAG_TSTAMP_SRC_SOE for start of exposure (next
> value).
>
> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Regards,
Hans
> ---
> since v5.1:
> - Remove the note on timestamp inaccuracy from SOE timestamps.
> - Add ..."or transmitted" for EOF timestamps.
> - Correct language related to valid buffer types and SOE timestamps.
>
> Documentation/DocBook/media/v4l/io.xml | 36 +++++++++++++++++++++++++-----
> drivers/media/v4l2-core/videobuf2-core.c | 4 +++-
> include/media/videobuf2-core.h | 2 ++
> include/uapi/linux/videodev2.h | 4 ++++
> 4 files changed, 39 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml
> index 46d24b3..d44401c 100644
> --- a/Documentation/DocBook/media/v4l/io.xml
> +++ b/Documentation/DocBook/media/v4l/io.xml
> @@ -653,12 +653,6 @@ plane, are stored in struct <structname>v4l2_plane</structname> instead.
> In that case, struct <structname>v4l2_buffer</structname> contains an array of
> plane structures.</para>
>
> - <para>For timestamp types that are sampled from the system clock
> -(V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC) it is guaranteed that the timestamp is
> -taken after the complete frame has been received (or transmitted in
> -case of video output devices). For other kinds of
> -timestamps this may vary depending on the driver.</para>
> -
> <table frame="none" pgwide="1" id="v4l2-buffer">
> <title>struct <structname>v4l2_buffer</structname></title>
> <tgroup cols="4">
> @@ -1119,6 +1113,36 @@ in which case caches have not been used.</entry>
> <entry>The CAPTURE buffer timestamp has been taken from the
> corresponding OUTPUT buffer. This flag applies only to mem2mem devices.</entry>
> </row>
> + <row>
> + <entry><constant>V4L2_BUF_FLAG_TSTAMP_SRC_MASK</constant></entry>
> + <entry>0x00070000</entry>
> + <entry>Mask for timestamp sources below. The timestamp source
> + defines the point of time the timestamp is taken in relation to
> + the frame. Logical and operation between the
> + <structfield>flags</structfield> field and
> + <constant>V4L2_BUF_FLAG_TSTAMP_SRC_MASK</constant> produces the
> + value of the timestamp source.</entry>
> + </row>
> + <row>
> + <entry><constant>V4L2_BUF_FLAG_TSTAMP_SRC_EOF</constant></entry>
> + <entry>0x00000000</entry>
> + <entry>End Of Frame. The buffer timestamp has been taken
> + when the last pixel of the frame has been received or the
> + last pixel of the frame has been transmitted. In practice,
> + software generated timestamps will typically be read from
> + the clock a small amount of time after the last pixel has
> + been received or transmitten, depending on the system and
> + other activity in it.</entry>
> + </row>
> + <row>
> + <entry><constant>V4L2_BUF_FLAG_TSTAMP_SRC_SOE</constant></entry>
> + <entry>0x00010000</entry>
> + <entry>Start Of Exposure. The buffer timestamp has been
> + taken when the exposure of the frame has begun. This is
> + only valid for the
> + <constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant> buffer
> + type.</entry>
> + </row>
> </tbody>
> </tgroup>
> </table>
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index 5a5fb7f..6e314b0 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -2195,7 +2195,9 @@ int vb2_queue_init(struct vb2_queue *q)
> WARN_ON(!q->io_modes) ||
> WARN_ON(!q->ops->queue_setup) ||
> WARN_ON(!q->ops->buf_queue) ||
> - WARN_ON(q->timestamp_type & ~V4L2_BUF_FLAG_TIMESTAMP_MASK))
> + WARN_ON(q->timestamp_type &
> + ~(V4L2_BUF_FLAG_TIMESTAMP_MASK |
> + V4L2_BUF_FLAG_TSTAMP_SRC_MASK)))
> return -EINVAL;
>
> /* Warn that the driver should choose an appropriate timestamp type */
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index bef53ce..b6b992d 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -312,6 +312,8 @@ struct v4l2_fh;
> * @buf_struct_size: size of the driver-specific buffer structure;
> * "0" indicates the driver doesn't want to use a custom buffer
> * structure type, so sizeof(struct vb2_buffer) will is used
> + * @timestamp_type: Timestamp flags; V4L2_BUF_FLAGS_TIMESTAMP_* and
> + * V4L2_BUF_FLAGS_TSTAMP_SRC_*
> * @gfp_flags: additional gfp flags used when allocating the buffers.
> * Typically this is 0, but it may be e.g. GFP_DMA or __GFP_DMA32
> * to force the buffer allocation to a specific memory zone.
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index e9ee444..82e8661 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -695,6 +695,10 @@ struct v4l2_buffer {
> #define V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN 0x00000000
> #define V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC 0x00002000
> #define V4L2_BUF_FLAG_TIMESTAMP_COPY 0x00004000
> +/* Timestamp sources. */
> +#define V4L2_BUF_FLAG_TSTAMP_SRC_MASK 0x00070000
> +#define V4L2_BUF_FLAG_TSTAMP_SRC_EOF 0x00000000
> +#define V4L2_BUF_FLAG_TSTAMP_SRC_SOE 0x00010000
>
> /**
> * struct v4l2_exportbuffer - export of video buffer as DMABUF file descriptor
>
next prev parent reply other threads:[~2014-02-23 11:36 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-15 20:52 [PATCH v5 0/7] Fix buffer timestamp documentation, add new timestamp flags Sakari Ailus
2014-02-15 20:52 ` [PATCH v5 1/7] v4l: Document timestamp behaviour to correspond to reality Sakari Ailus
2014-02-15 20:53 ` [PATCH v5 2/7] v4l: Use full 32 bits for buffer flags Sakari Ailus
2014-02-17 8:46 ` Hans Verkuil
2014-02-23 11:49 ` Hans Verkuil
2014-02-24 15:34 ` Sakari Ailus
2014-02-24 16:02 ` Hans Verkuil
2014-02-24 17:57 ` Laurent Pinchart
2014-02-24 16:13 ` Kamil Debski
2014-02-25 11:44 ` 'Sakari Ailus'
2014-02-25 12:02 ` Hans Verkuil
2014-02-15 20:53 ` [PATCH v5 3/7] v4l: Add timestamp source flags, mask and document them Sakari Ailus
2014-02-17 8:54 ` Hans Verkuil
2014-02-17 23:29 ` Sakari Ailus
2014-02-20 19:41 ` [PATCH v5.1 " Sakari Ailus
2014-02-20 20:36 ` Hans Verkuil
2014-02-20 21:10 ` Sylwester Nawrocki
2014-02-20 21:20 ` Sylwester Nawrocki
2014-02-21 9:51 ` Sakari Ailus
2014-02-20 23:30 ` Laurent Pinchart
2014-02-21 7:17 ` Hans Verkuil
2014-02-21 9:31 ` Sakari Ailus
2014-02-21 11:58 ` Laurent Pinchart
2014-02-21 13:04 ` Sakari Ailus
2014-02-21 13:19 ` Laurent Pinchart
2014-02-23 10:40 ` [PATCH v5.2 " Sakari Ailus
2014-02-23 11:36 ` Hans Verkuil [this message]
2014-02-25 13:09 ` [PATCH v5 " Kamil Debski
2014-02-26 0:09 ` 'Sakari Ailus'
2014-02-15 20:53 ` [PATCH v5 4/7] uvcvideo: Tell the user space we're using start-of-exposure timestamps Sakari Ailus
2014-02-17 0:51 ` Laurent Pinchart
2014-02-15 20:53 ` [PATCH v5 5/7] exynos-gsc, m2m-deinterlace, mx2_emmaprp: Copy v4l2_buffer data from src to dst Sakari Ailus
2014-02-25 13:08 ` Kamil Debski
2014-02-15 20:53 ` [PATCH v5 6/7] v4l: Copy timestamp source flags to destination on m2m devices Sakari Ailus
2014-02-25 13:08 ` Kamil Debski
2014-02-15 20:53 ` [PATCH v5 7/7] v4l: Document timestamp buffer flag behaviour Sakari Ailus
2014-02-15 21:03 ` Hans Verkuil
2014-02-16 17:50 ` Sakari Ailus
2014-02-17 0:56 ` Laurent Pinchart
2014-02-17 8:43 ` Hans Verkuil
2014-02-17 23:32 ` Sakari Ailus
2014-02-17 23:33 ` Sakari Ailus
2014-02-20 19:42 ` [PATCH v5.1 " Sakari Ailus
2014-02-20 20:25 ` Hans Verkuil
2014-02-23 10:39 ` Sakari Ailus
2014-02-23 11:45 ` [PATCH v5 " Hans Verkuil
2014-02-25 17:08 ` Sakari Ailus
2014-02-25 17:28 ` Hans Verkuil
2014-02-26 0:04 ` Sakari Ailus
2014-02-26 0:07 ` Hans Verkuil
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