diff options
author | Marvin Lin <milkfafa@gmail.com> | 2023-09-22 09:24:04 +0300 |
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committer | Hans Verkuil <hverkuil-cisco@xs4all.nl> | 2023-09-27 10:40:02 +0300 |
commit | 1568583b3977f232e6e7a652fd4be95a11d0ecae (patch) | |
tree | 52e3baf97b562c5b5a9b726a82b1a9fb0a66310a /Documentation/userspace-api | |
parent | 2817154cd18942cd89e254d3764a378518a3270f (diff) | |
download | linux-1568583b3977f232e6e7a652fd4be95a11d0ecae.tar.xz |
media: uapi: Add controls for NPCM video driver
Create controls for Nuvoton NPCM video driver to support setting
capture mode of Video Capture/Differentiation (VCD) engine and getting
the count of HEXTILE rectangles that is compressed by Encoding
Compression Engine (ECE).
Signed-off-by: Marvin Lin <milkfafa@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Diffstat (limited to 'Documentation/userspace-api')
-rw-r--r-- | Documentation/userspace-api/media/drivers/index.rst | 1 | ||||
-rw-r--r-- | Documentation/userspace-api/media/drivers/npcm-video.rst | 66 |
2 files changed, 67 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/drivers/index.rst b/Documentation/userspace-api/media/drivers/index.rst index 6708d649afd7..783f92f01a4c 100644 --- a/Documentation/userspace-api/media/drivers/index.rst +++ b/Documentation/userspace-api/media/drivers/index.rst @@ -37,6 +37,7 @@ For more details see the file COPYING in the source distribution of Linux. dw100 imx-uapi max2175 + npcm-video omap3isp-uapi st-vgxy61 uvcvideo diff --git a/Documentation/userspace-api/media/drivers/npcm-video.rst b/Documentation/userspace-api/media/drivers/npcm-video.rst new file mode 100644 index 000000000000..b47771dd8b27 --- /dev/null +++ b/Documentation/userspace-api/media/drivers/npcm-video.rst @@ -0,0 +1,66 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. include:: <isonum.txt> + +NPCM video driver +================= + +This driver is used to control the Video Capture/Differentiation (VCD) engine +and Encoding Compression Engine (ECE) present on Nuvoton NPCM SoCs. The VCD can +capture a frame from digital video input and compare two frames in memory, and +the ECE can compress the frame data into HEXTILE format. + +Driver-specific Controls +------------------------ + +V4L2_CID_NPCM_CAPTURE_MODE +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The VCD engine supports two modes: + +- COMPLETE mode: + + Capture the next complete frame into memory. + +- DIFF mode: + + Compare the incoming frame with the frame stored in memory, and updates the + differentiated frame in memory. + +Application can use ``V4L2_CID_NPCM_CAPTURE_MODE`` control to set the VCD mode +with different control values (enum v4l2_npcm_capture_mode): + +- ``V4L2_NPCM_CAPTURE_MODE_COMPLETE``: will set VCD to COMPLETE mode. +- ``V4L2_NPCM_CAPTURE_MODE_DIFF``: will set VCD to DIFF mode. + +V4L2_CID_NPCM_RECT_COUNT +~~~~~~~~~~~~~~~~~~~~~~~~ + +If using V4L2_PIX_FMT_HEXTILE format, VCD will capture frame data and then ECE +will compress the data into HEXTILE rectangles and store them in V4L2 video +buffer with the layout defined in Remote Framebuffer Protocol: +:: + + (RFC 6143, https://www.rfc-editor.org/rfc/rfc6143.html#section-7.6.1) + + +--------------+--------------+-------------------+ + | No. of bytes | Type [Value] | Description | + +--------------+--------------+-------------------+ + | 2 | U16 | x-position | + | 2 | U16 | y-position | + | 2 | U16 | width | + | 2 | U16 | height | + | 4 | S32 | encoding-type (5) | + +--------------+--------------+-------------------+ + | HEXTILE rectangle data | + +-------------------------------------------------+ + +Application can get the video buffer through VIDIOC_DQBUF, and followed by +calling ``V4L2_CID_NPCM_RECT_COUNT`` control to get the number of HEXTILE +rectangles in this buffer. + +References +---------- +include/uapi/linux/npcm-video.h + +**Copyright** |copy| 2022 Nuvoton Technologies |