- Generated on Wed Jun 5 2024 23:23:15 for Software Genlock by
1.9.1
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Software Genlock
v2.0.0
Digital Signage SW Library for adjusting VSYNC timings via MMIO PLL register modifications.
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Copyright (C) 2023 Intel Corporation SPDX-License-Identifier: MIT
This program allows a system to alter their vertical sync firing times. This is sample code only and is only supported on 11th Gen Core. Please note that this document was written based on Ubuntu
The build system assumes the following, prior to executing the build steps: 1) The system has an Ubuntu OS 1) Libraries installed: sudo apt install -y git build-essential make 1) Disable secure boot 1) You MUST apply the PLL kernel patch.
update-grub ```
1) Git clone this repository 1) sudo apt install libdrm-dev libpciaccess-dev 1) If the directory /usr/include/drm does not exist, you may need to also add sudo apt install -y linux-libc-dev 1) Type make release from the main directory. It compiles everything and creates a release folder which can then be copied to the target systems.
You can turn on debug printing automatically by building with make debug There is a dbg_lvl flag which can be set to INFO, DBG, ERR etc.
sample output:
If you are doing debug, it helps to have the following libraries installed:
If you are encountering unexpected behavior that requires additional debug, the tools installed can assist with narrowing the potential problem.
intel-gpu-tools Provides tools to read and write to registers, it must be run as the root user. Example:
edid-decode is a tool used to parse the Extended Display Identification Data (EDID) from monitors and display devices. EDID contains metadata about the display's capabilities, such as supported resolutions, manufacturer, serial number, and other attributes.
To run edid-decode, you typically need to provide it with a binary EDID file or data. Sample usage:
Please install doxygen and graphviz packages before generating Doxygen documents: sudo apt install doxygen graphviz
make doxygen VERSION="1.2.3" from the main directory. It will generate SW Genlock doxygen documents to output/doxygen folder. Change the version to be that of the release number for the project.1) On the system, go to the directory where these files exist and set environment variable:
Building of this program has been successfully tested on both Ubuntu 2x and Fedora 30.
In order to prepare two systems, please follow these steps:
drm.timestamp_monotonic=0 option to GRUB_CMDLINE_LINUX in /etc/default/grubupdate-grub to apply the changetimedatectl set-ntp noRun ptp sync on both the systems as root user.
On the primary system, run the following command: ptp4l -i enp176s0 -m -f gPTP.cfg
On the secondary system, run the following command: ptp4l -i enp176s0 -m -f gPTP.cfg -s
There must be a gPTP.cfg file present in the same directory from where you run the above two commands. The contents of this file should look like this:
```shell
[global] gmCapable 1 priority1 248 priority2 248 logAnnounceInterval 0 logSyncInterval -3 syncReceiptTimeout 3 neighborPropDelayThresh 15000 min_neighbor_prop_delay -20000000 assume_two_step 1 path_trace_enabled 1 follow_up_info 1 transportSpecific 0x1 network_transport L2 delay_mechanism P2P ```
The output on the primary system after running the above command should look like this:
```console ptp4l[13416.983]: selected /dev/ptp1 as PTP clock ptp4l[13417.002]: port 1: INITIALIZING to LISTENING on INIT_COMPLETE ptp4l[13417.003]: port 0: INITIALIZING to LISTENING on INIT_COMPLETE ptp4l[13420.445]: port 1: LISTENING to MASTER on ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES ptp4l[13420.445]: selected local clock 844709.fffe.04f07f as best master ptp4l[13420.445]: assuming the grand master role ```
The output on the secondary system after running the above command should look like this:
```console ptp4l[14816.313]: selected /dev/ptp1 as PTP clock ptp4l[14816.328]: port 1: INITIALIZING to LISTENING on INIT_COMPLETE ptp4l[14816.328]: port 0: INITIALIZING to LISTENING on INIT_COMPLETE ptp4l[14820.220]: port 1: new foreign master 844709.fffe.04f07f-1 ptp4l[14820.250]: selected local clock 844709.fffe.04eb0e as best master ptp4l[14822.220]: selected best master clock 844709.fffe.04f07f ptp4l[14822.220]: port 1: LISTENING to UNCALIBRATED on RS_SLAVE ptp4l[14822.650]: port 1: UNCALIBRATED to SLAVE on MASTER_CLOCK_SELECTED ptp4l[14823.275]: rms 158899 max 317730 freq -11742 +/- 3075 delay 14 +/- 0 ptp4l[14824.276]: rms 820 max 1257 freq -9067 +/- 1113 delay 14 +/- 0 ptp4l[14825.277]: rms 1366 max 1436 freq -6582 +/- 359 delay 13 +/- 0 ptp4l[14826.278]: rms 866 max 1148 freq -6099 +/- 34 delay 13 +/- 0 ptp4l[14827.279]: rms 280 max 465 freq -6364 +/- 102 delay 12 +/- 0 ptp4l[14828.280]: rms 52 max 80 freq -6666 +/- 65 delay 12 +/- 0 ptp4l[14829.280]: rms 82 max 88 freq -6805 +/- 21 delay 12 +/- 0 ptp4l[14830.281]: rms 50 max 69 freq -6829 +/- 3 delay 12 +/- 0 ptp4l[14831.282]: rms 15 max 28 freq -6811 +/- 7 delay 12 +/- 0 ptp4l[14832.283]: rms 4 max 8 freq -6795 +/- 5 delay 12 +/- 0 ptp4l[14833.284]: rms 7 max 10 freq -6783 +/- 3 delay 12 +/- 0 ptp4l[14834.285]: rms 2 max 5 freq -6788 +/- 3 delay 13 +/- 0 ptp4l[14835.286]: rms 3 max 5 freq -6793 +/- 3 delay 13 +/- 0 ```
Please make it sure that the secondary sytem refers to the primary's precision time by checking if there is the __"new foreign master"__ message in a log
Note that the rms value should be decreasing with each line and should go down to single digits.
phc2sys -s enp176s0 -O 0 -R 8 -u 8 -mInstalling and running the programs:
./vsync_test pri [PTP_ETH_Interface]./vsync_test sec PTP_ETH_Interface [Primary_ETH_MAC_Addr] [sync after # us]This program runs in server mode on the primary system and in client mode on the secondary system.
If using PTP protocol to communicate between primary and secondary, there are some extra parameters required. The primary system must identify the PTP Interface (ex: enp176s0). The secondary system also requires its PTP interface as well as this port's ethernet MAC address. An example of PTP communication between primary and secondary looks like this: On the primary system, run it as follows: ./vsync_test pri enp176s0
On the secondary system, run it as follows: ./vsync_test sec enp176s0 84:47:09:04:eb:0e
In the above examples, we were just sync'ing the secondary system once with the primary. However, due to reference clock differences, we see that there is a drift pretty much as soon as we have sync'd them. We also have another capability which allows us to resync as soon as it goes above a threshold. For example:
On the primary system, run it as follows: ./vsync_test pri enp176s0
On the secondary system, run it as follows: ./vsync_test sec enp176s0 84:47:09:04:eb:0e 100
In the above example, secondary system would sync with the primary once but after that it would constantly check to see if the drift is going above 100 us. As soon as it does, the secondary system would automatically resync with the primary. It is recommended to select a large number like 60 or 100 since if we use a smaller number, then we will be resyncing all the time. On the other hand, if we chose a really big number like 1000 us, then we are allowing the systems to get out of sync from each other for 1 ms. On a Tiger Lake system, 100 us difference is usually happening in around 60-70 seconds or about a minute. So this program would automatically resync with the primary every minute or so.
1.9.1