Table of Contents
The purpose of this page is to describe the Linux V4L2 driver for Xilinx VPSS Scaler soft IP. VPSS refers to the Video Processing Sub System.
To understand more about the capabilities of this IP please see the Product Guide (Scaler Only configuration) for VPSS.
|IP features||2018.1 to 2018.3||2019.1||2019.2 - 2021.2|
|One, two or four pixel-wide AXI4-Stream video interface||Yes*|
Supports 1,2,4 and 8 ppc
Driver supports 1,2 and 4
|Video resolution support up to UHD at 60 fps||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 and 10 bpc formats using 8 and 10 bpc media bus formats
|Yes** Driver supports only 8 and 10 bpc formats using 8 and 10 bpc media bus formats|
|Bilinear, Bicubic and polyphase algorithms supported.||Yes***|
Missing Features / Known Issues / Limitations in Driver
- Colorspace support options are limited to only RGB | YUV 4:4:4 | YUV 4:2:2 | YUV 4:2:0. All other colorspace options are not supported in this release.
- *The maximum samples per clock supported by the Linux Driver is 1 and 2 (also called pixels per clock). 4 pixels per clock is not supported.
- **12 and 16 bit color depth is not supported by this driver.
- **Maximum color depth supported by the VPSS Scaler soft IP driver is limited to 8-bit and 10-bit in this release.
- ***Asymmetrical scaler taps are not supported. Horizontal taps must be same as Vertical taps.
- Fixed coefficients are used in the driver. In future, this may be an input from application.
Video Processing Subsystem Release Notes and Known Issues
CONFIG_VIDEO_XILINX_VPSS_SCALER 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:https://github.com/Xilinx/linux-xlnx/blob/master/Documentation/devicetree/bindings/media/xilinx/xlnx%2Cv-vpss-scaler.txt
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)
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 driver has been tested with a design having TPG + VTC feeding video to VPSS Scaler connected to Framebuffer Write.
/* Setup TPG color bar pattern */
media-ctl -v -V '"a3c30000.tpg":0 [fmt:RBG24/1920x1080 field:none]'
media-ctl -v -V '"a3c40000.csc":1 [fmt:RBG24/1280x720 field:none]'
yavta -n3 -c15 -f RGB24 -s1280x720 --skip 12 -F /dev/video0
Frame Scaling or Resizing:
This media-ctl and yavta commands capture frames down scaled from 1920x1080 to 1280x720 in RGB888 format.
Scaling using bilinear, bicubic and poly-phase (6, 8, 10 and 12 tap) filters that use coefficients programmed by the driver.
Color Space Conversion. All color space conversions have been tested.
#VPSS: Scaler Only with CSC Upscale from 720p to 1080p and changing the color space from RGB to YUV 4:2:0
media-ctl -d /dev/media7 -V '"a0080000.v_proc_ss":0 [fmt:RBG888_1X24/1280x720 field:none]'
media-ctl -d /dev/media7 -V '"a0080000.v_proc_ss":1 [fmt:VYYUYY8_1X24/1920x1080 field:none]'
Scaling Formats that have been tested are as follow :
Generally arbitrary scaling resolutions are also supported
|Sr No.||Video Input Resolution||Video Output Resolution|
(limited to a maximum of 3840x2160 and a minimum of 224X128).
Driver has been tested on following boards:
- ZCU102 Rev 1.0
- ZCU106 Rev 1.0
- AR65449 - LogiCORE IP Video Processing Subsystem(VPSS) - Release Notes and Known Issues for the Vivado 2015.3 tool and later versions
- Expect better quality output on account of more coefficient tables per scale ratio range
- Add support for 4 ppc
- Add support for v2.2 of IP version (change in HPHASE base address from 0x2000 to 0x4000)
- Add support for 10bpc media bus formats
- Make max-width and max-height mandatory dt properties
- Fix common clock framework support.
dcfaa72 v4l: xilinx: vpss-scaler: Use 10bit media bus codes
e5e28c8 v4l: xilinx: vpss-scaler: Make max width and height mandatory properties
f71ea37 v4l: xilinx: vpss-scaler: Fix clock framework support
- Fix array out of bound access leading to random kernel crash
- Add check for max width and height from device tree
fd5d5b4 v4l: xilinx: vpss-scaler: Correct default values when max width, height dt property absent
59fc4b5 v4l: xilinx: vpss-scaler: Fix array out of bound access
2966837 v4l: xilinx-vpss-scaler: Add check for max width and height
- Clear the H-phase array to fix repeated pixels seen in up-scaling video
- Add YUV 420 support
- Add initial version of the driver
d136f7c v4l: xilinx-vpss-scaler: Fix phase calculation
3f17edf v4l: xilinx-vpss-scaler: fix dev_dbg logging typo and remove dead code
2ae0fd4 v4l: xilinx-vpss-scaler: fix logical error in pixels per clock check
0c99a1e v4l: xilinx-vpss-scaler: add bilinear and bicubic scaling support
ee7f2ef v4l: xilinx-vpss-scaler: driver support for xilinx vpss scaler