Why is the manual lock to reference mode of the GTS transceivers in Agilex™ 5 FPGA not working as expected?

Description

Due to a problem in the Quartus® Prime Pro Edition software version 25.1.1 and earlier, the manual lock to reference mode of the GTS transceivers in Agilex™ 5 FPGA does not work as expected.

Resolution

For a workaround, users will need to follow the following steps to enable the manual lock to reference mode to function properly. 

• Write 0x1 to 0x818 [0] for Software Reset Controller(SRC) to ignore the CDR LTD status. 
• Write 0x1 to both 0x91680 [24] and 0x91680 [28] for enabling LTR mode 
• Write 0x1 to both 0x91580 [30] and 0x91580 [31] for enabling RX parallel data in manual LTR mode  

The manual LTR mode will only work when adaptation is set to manual. 

This problem is scheduled to be fixed in a future release of the Quartus® Prime Pro Edition software.