alt2gxb: pll_locked keeps low

basic mode

refclk 50M diven by input pin

primary data rate:1000M

serial loopback.

reset flow: gxb_powerdown->when pll_locked->deassert tx_digitalreset and rx_analogreset.....

the project can work well last week either in loopback mode or not.

but today, the serdes can not work, I found the reason is that trasmitter PLL can not lock, the pll_locked signal keeps low.

is it a Quartus's IP bug? 9.1 sp1:confused:

regards.