For Vivado 2021.1 and 2021.1.1 the Clock Calibrated Deskew will be used and you will need to apply the attached patch.
When Calibrated Clock Deskew is used, the following message is seen in Vivado to indicate that this feature is enabled.
INFO: [Constraints 18-5720] The default GCLK Deskew mode is Calibrated.
After you have applied the attached patch, the design will need to be re-implemented and you can verify that it has been applied by checking the Vivado log.
Vivado 2021.2.x has this feature disabled by default and therefore will not be impacted.
| Vivado version | Clock Calibrated Deskew Default Setting |
| 2020.3 and earlier | Off |
| 2021.1 and 2021.1.1 | On *patch required |
| 2021.2 and 2021.2.1 | Off |
| 2022.1 | Dependent on device and speed file designation (see table below), no patch is required (See Vivado 2022.1 - Versal Clock Calibrated Deskew Timing issues ) |
| 2022.2 | Dependent on device and speed file designation (see table below), no patch is required (See 000034546 - Vivado 2022.2 - Versal Clock Calibrated Deskew Timing issues ) |
| 2023.x and 2022.2.2 | Dependent on device and speed file designation (see table below), no patch is required (See Vivado 2022.2.2 - Versal Clock Calibrated Deskew Timing issues ) |
Note: The tactical patch attached to this answer record also provides fixes for the following issues. A common patch has been provided for ease of use.
Deskew Phase Detector (i.e. using CLKIN_DESKEW, CLKFB_DESKEW pins) on the Clock Managers in Vivado 2021.1.x and earlier can result in incorrect timing being reported by Vivado timing.
[1] This can impact the CPM4 which uses the DPLL with Deskew Phase Detector, see 76947 - Versal ACAP CPM Mode for PCI Express (Vivado 2021.1) - Potential timing issue with designs that have CPM4 to PL interfaces enabled
[2] This can impact the MMCM if using CLKIN_DESKEW or CLKFB_DESKEW pins, see 76908 - Vivado 2021.1 Vivado Versal Clocking : Deskew logic for MMCM and DPLL are timed incorrectly
Revision History:
- 22 Oct 2021 - Initial Release
- 13 Dec 2021 - Updated with Vivado 2021.2 details and added table with Vivado version and Default Setting
- 11 Oct 2022 - Updated with Vivado 2022.1 behavior by device and link to Answer Record
- 09 Nov 2022 - Updated with Vivado 2022.2 behavior by device and link to Answer Record
- 03 Apr 2023 - Updated with Vivado 2022.2.2 behavior by device and link to Answer Record
- 15 August 2023 - Updated with Vivado 2023.x added to existing 2022.2.2 Answer Record