From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
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@xxxxxxxxx>
---
.../media/uapi/v4l/vidioc-g-dv-timings.rst | 27 +++++++++++++------
1 file 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.
--
2.18.0
