diff options
| author | Sakari Ailus | 2021-06-22 13:17:20 +0200 |
|---|---|---|
| committer | Mauro Carvalho Chehab | 2021-08-04 14:43:50 +0200 |
| commit | e5a466d4bcf962daa8fea589b09a5675bda275a1 (patch) | |
| tree | 2c896b4e01323e1ae741928f751044fb941e0d3a /Documentation/userspace-api | |
| parent | 8925b53083980057de99599ba8dd2a72b03406a6 (diff) | |
media: Documentation: v4l: Improve frame rate configuration documentation
Improve the documentation of the frame rate configuration so that it can
be understood by a regular human being.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Diffstat (limited to 'Documentation/userspace-api')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst | 23 |
1 files changed, 10 insertions, 13 deletions
diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst index 2b5a13dc843f..b1c2ab2854af 100644 --- a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst @@ -23,19 +23,7 @@ Image Process Control IDs .. _v4l2-cid-link-freq: ``V4L2_CID_LINK_FREQ (integer menu)`` - Data bus frequency. Together with the media bus pixel code, bus type - (clock cycles per sample), the data bus frequency defines the pixel - rate (``V4L2_CID_PIXEL_RATE``) in the pixel array (or possibly - elsewhere, if the device is not an image sensor). The frame rate can - be calculated from the pixel clock, image width and height and - horizontal and vertical blanking. While the pixel rate control may - be defined elsewhere than in the subdev containing the pixel array, - the frame rate cannot be obtained from that information. This is - because only on the pixel array it can be assumed that the vertical - and horizontal blanking information is exact: no other blanking is - allowed in the pixel array. The selection of frame rate is performed - by selecting the desired horizontal and vertical blanking. The unit - of this control is Hz. + The frequency of the data bus (e.g. parallel or CSI-2). .. _v4l2-cid-pixel-rate: @@ -43,6 +31,15 @@ Image Process Control IDs Pixel sampling rate in the device's pixel array. This control is read-only and its unit is pixels / second. + Some devices use horizontal and vertical balanking to configure the frame + rate. The frame rate can be calculated from the pixel rate, analogue crop + rectangle as well as horizontal and vertical blanking. The pixel rate + control may be present in a different sub-device than the blanking controls + and the analogue crop rectangle configuration. + + The configuration of the frame rate is performed by selecting the desired + horizontal and vertical blanking. The unit of this control is Hz. + ``V4L2_CID_TEST_PATTERN (menu)`` Some capture/display/sensor devices have the capability to generate test pattern images. These hardware specific test patterns can be |