Xilinx V4L2 VPSS CSC driver
Table of Contents
Introduction
The purpose of this page is to describe the Linux V4L2 driver for Xilinx VPSS Color Space Converter (CSC) soft IP. VPSS refers to the Video Processing Sub System.
This driver is for the CSC only mode of operation in the VPSS, please see the Product Guide for more details on its functionality and features.
The Linux VPSS CSC driver (xilinx-vpss-csc.c) based on the V4L2 framework creates a subdev node(/dev/v4l-subdev*) which can be used to configure the VPSS CSC IP core. The VPSS CSC supports changing video properties through V4L Controls like Brightness, Contrast, Red Gain, Blue Gain and Green Gain. The driver is available at https://github.com/Xilinx/linux-xlnx/blob/master/drivers/media/platform/xilinx/xilinx-vpss-csc.c
The VPSS CSC driver supports only the following features are supported including:
Ability apply controls Brightness and Contrast.
Ability to apply controls Red, Green and Blue gains.
The CSC IP will look like the following when displayed through media-ctl
entity 7: a0040000.csc (2 pads, 2 links) type V4L2 subdev subtype Unknown flags 0 device node name /dev/v4l-subdev1 pad0: Sink [fmt:RBG24/1280x720 field:none] <- "a0050000.gamma":1 [ENABLED] pad1: Source [fmt:RBG24/1280x720 field:none] -> "a0000000.scalar":0 [ENABLED]
yavta can be used to modify the control supported by the V4L2 VPSS CSC Driver
root@plnx_aarch64:~# yavta --no-query -l /dev/v4l-subdev1 Device /dev/v4l-subdev1 opened. --- User Controls (class 0x00980001) --- control 0x0098c9a1 `CSC Brightness' min 0 max 100 step 1 default 50 current 50. control 0x0098c9a2 `CSC Contrast' min 0 max 100 step 1 default 50 current 50. control 0x0098c9a3 `CSC Red Gain' min 0 max 100 step 1 default 50 current 50. control 0x0098c9a4 `CSC Green Gain' min 0 max 100 step 1 default 50 current 50. control 0x0098c9a5 `CSC Blue Gain' min 0 max 100 step 1 default 50 current 50. 5 controls found. root@plnx_aarch64:~# yavta --no-query -w '0x0098c9a1 80' /dev/v4l-subdev1 Device /dev/v4l-subdev1 opened. Control 0x0098c9a1 set to 80, is 80 root@plnx_aarch64:~# yavta --no-query -l /dev/v4l-subdev1 Device /dev/v4l-subdev1 opened. --- User Controls (class 0x00980001) --- control 0x0098c9a1 `CSC Brightness' min 0 max 100 step 1 default 50 current 80. control 0x0098c9a2 `CSC Contrast' min 0 max 100 step 1 default 50 current 50. control 0x0098c9a3 `CSC Red Gain' min 0 max 100 step 1 default 50 current 50. control 0x0098c9a4 `CSC Green Gain' min 0 max 100 step 1 default 50 current 50. control 0x0098c9a5 `CSC Blue Gain' min 0 max 100 step 1 default 50 current 50. 5 controls found.
IP/Driver Features
IP features | 2018.1 to 2018.3 | 2019.1 |
|---|---|---|
One, two or four pixel-wide AXI4-Stream video interface | Yes | |
Compatible string | xlnx,v-vpss-csc (2023.1 and above) | |
Video resolution support up to UHD at 60 fps | Yes | |
Run-time color space support for RGB, YUV 4:4:4, YUV 4:2:2, YUV 4:2:0 | Yes | |
8, 10, 12, and 16 bits per component support | Driver supports only 8 and 10 bpc formats using only 8 bpc MEDIA BUS formats. | Yes* Driver supports only 8, 10 and 12 bpc formats using 8, 10 and 12 bpc media bus formats |
Missing Features / Known Issues / Limitations in Driver
Works with fixed Vivado IP configuration as highlighted.
Demo Window is not supported
Does not support this driver in VPSS IPs full fledged mode.
*Maximum color depth supported by the VPSS CSC soft IP driver is limited to 8, 10 and 12 bpc.
*16 bpc color depth width is not supported.
Saturation Control is not supported
Pre-computed color conversion coefficient matrix used.
In future user supplied custom coefficients support may be added.
Video Processing Subsystem Release Notes and Known Issues
Kernel Configuration
CONFIG_VIDEO_XILINX_VPSS_CSC and CONFIG_VIDEO_XILINX should be enabled.
Device tree binding
The dts node should be defined with correct hardware configuration. How to define the node is documented here: VPSS CSC dt-bindings documentation
Testing Procedure
This driver is a V4L2 sub-device driver, which means it is designed to operate with a video device in it's graph. The driver has been tested with a Xilinx video device (a V4L2 capture device) that is backed by a DMA element (like Framebuffer Write IP). The V4L2 device driver for this IP cannot be tested in isolation by itself. The successful operation of the driver can be tested in two phases :
Successful Creation of a Media Device
Successful Frame Captures (or writing of buffers by the Frame-buffer Write IP)
Successful Creation of a Media Device
media-ctl is a Linux user space utility that can control media entities, it is a part of a larger set of V4L2 tools called v4l-utils
media-ctl allows you to print the topology of your media pipeline and specify input and output pad properties.
Successful Frame Captures
Please see the Test Approach section of the Frame Buffer Write Wiki for more details on how to capture frames.
The Red / Green / Blue gain values can be changed as shown in the Overview section and the captured images can be compared.
Test design
We need a ZCU102 Rev 1.0 board. Enable TPG, VPSS CSC and Framebuffer Write in kernel defconfig.
The color format set in the TPG is what will propagate to CSC sink pad.
The color format set in the CSC source pad and the one set on video node (Framebuffer Write) in yavta should match.
The device tree also needs to be update. If we are using a 8 bit design then TPG output video-width, VPSS CSC input and output ports video-width should all be 8.
For 10bpc design, the video-width is 10. The video-format for the TPG output port and VPSS CSC input port should match.
/* Use yavta to setup the color bar pattern */
#Set up the TPG output color format to RGB888
media-ctl -v -V '"a3c30000.tpg":0 [fmt:RBG888_1X24/1280x720 field:none]'
#Set up the Color Space convertor output to YUV 422
media-ctl -v -V '"a3c40000.csc":1 [fmt:UYVY8_1X16/1280x720 field:none]'
#Start capture
yavta -n3 -c15 -f YUYV -s1280x720 --skip 14 -F /dev/video0View the captured files in some viewer like yuvplayer.exe.
Boards Supported
Driver has been tested on following boards:
ZCU102 Rev 1.0
Known Issues
AR65449 - LogiCORE IP Video Processing Subsystem(VPSS) - Release Notes and Known Issues for the Vivado 2015.3 tool and later versions
Change log
2025.2
No changes
2025.1
Summary
Add YUV444 12-bit media bus format
2024.2
No changes
2024.1
No changes
2023.2
No changes
2023.1
No changes
2022.2
No changes
2022.1
No changes
2021.2
Summary
Update the SPDX license header
Preserve the control values on setting format
Commits
v4l: xilinx: vpss-csc: Update SPDX license header
2021.1
No changes
2020.2
Summary
Fix Coverity warnings
Commits
2020.1
Summary
No changes
2019.2
Summary
Add support for missing RGB 10bpc media bus format
Commits
2764687 v4l: xilinx: vpss-csc: Fix xcsc_set_format() for RBG 10 bpc
2019.1
Summary
Use 10 bit media codes
Make max-width and max-height as mandatory dt properties
Commits
2018.3
Summary
Add check for max width and height from dt
Commits
dddf225 v4l: xilinx-vpss-csc: Add check for max width and height
2018.2
Summary
No changes
2018.1
Summary
Support for any to any color space conversion
Commits
3592a90 v4l: xilinx-vpss-csc: Support for any-to-any color space converison
2017.4
Summary
No changes
2017.3
Summary
Initial driver version added
Commits
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