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authorHans Verkuil <hans.verkuil@cisco.com>2018-08-15 16:10:59 +0300
committerMauro Carvalho Chehab <mchehab+samsung@kernel.org>2018-08-31 16:31:28 +0300
commita125385c9b17de4e555cc2057593ab11da5edc70 (patch)
treee83af99c720a4c0aa7caea2542a5cfb476812c95 /Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst
parentfb98e29ff1ea5a8118265d11f0e03bc8608a49cb (diff)
downloadlinux-a125385c9b17de4e555cc2057593ab11da5edc70.tar.xz
media: vidioc-g-dv-timings.rst: document V4L2_DV_FL_CAN_DETECT_REDUCED_FPS
Document the new V4L2_DV_FL_CAN_DETECT_REDUCED_FPS flag and update the V4L2_DV_FL_REDUCED_FPS description since it can now also be used with receivers. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Diffstat (limited to 'Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst')
-rw-r--r--Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst27
1 files changed, 19 insertions, 8 deletions
diff --git a/Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst b/Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst
index 1a034e825161..35cba2c8d459 100644
--- a/Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst
+++ b/Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst
@@ -257,14 +257,19 @@ EBUSY
will also be cleared. This is a read-only flag, applications must
not set this.
* - ``V4L2_DV_FL_REDUCED_FPS``
- - CEA-861 specific: only valid for video transmitters, the flag is
- cleared by receivers. It is also only valid for formats with the
- ``V4L2_DV_FL_CAN_REDUCE_FPS`` flag set, for other formats the
- flag will be cleared by the driver. If the application sets this
- flag, then the pixelclock used to set up the transmitter is
- divided by 1.001 to make it compatible with NTSC framerates. If
- the transmitter can't generate such frequencies, then the flag
- will also be cleared.
+ - CEA-861 specific: only valid for video transmitters or video
+ receivers that have the ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS``
+ set. This flag is cleared otherwise. It is also only valid for
+ formats with the ``V4L2_DV_FL_CAN_REDUCE_FPS`` flag set, for other
+ formats the flag will be cleared by the driver.
+
+ If the application sets this flag for a transmitter, then the
+ pixelclock used to set up the transmitter is divided by 1.001 to
+ make it compatible with NTSC framerates. If the transmitter can't
+ generate such frequencies, then the flag will be cleared.
+
+ If a video receiver detects that the format uses a reduced framerate,
+ then it will set this flag to signal this to the application.
* - ``V4L2_DV_FL_HALF_LINE``
- Specific to interlaced formats: if set, then the vertical
backporch of field 1 (aka the odd field) is really one half-line
@@ -294,3 +299,9 @@ EBUSY
- If set, then the hdmi_vic field is valid and contains the Video
Identification Code as per the HDMI standard (HDMI Vendor Specific
InfoFrame).
+ * - ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS``
+ - CEA-861 specific: only valid for video receivers, the flag is
+ cleared by transmitters.
+ If set, then the hardware can detect the difference between
+ regular framerates and framerates reduced by 1000/1001. E.g.:
+ 60 vs 59.94 Hz, 30 vs 29.97 Hz or 24 vs 23.976 Hz.