GBT reset link

For debugging, it would really be helpful to have a way to reset the GBT links in the CRU similar to what is done in the GBT_FPGA example designs from the GBT group. The main reason for ITS would be to have a way to force the RU firmware to resync the elinks. Does such a feature already exist in the CRU firmware and if so, how does one use it?


At the moment, the MGT transceivers are only reseted once at startup (the reset pin is not connected) by the RTL. Then we do a to calibrate the transceivers.

So if you need this we will have to modify the RTL (actually we’ll do it). Currently the gbt core functions are being upgraded to the latest version released by the GBT team. It should happen this week if we encounter no problems.

The will be updated to perform this reset every-time it is called.


Possible workaround: In the past when I needed to reestablish the connection with the GBTx on the VLDB board I used the txinv command from the If you invert the TX serial stream for a short time, the partner will loose the GBT connection because even the header pattern will change.