Stratix V GX SI Dev Kit - Sometimes no link in Transceiver Toolkit

[Altera_Forum]

Hello, 

i am using the mentioned board and successfully tested an external transceiver loop with the examples (10312 mbps). I also changed the phy in qsys to fractions of 10312 mbps whichs works as long as the reference clock remains constant.  Now I changed to 6000 mbps with 300 MHz and i get no link, also 12500 mbps with 500 MHz refclk.  In another case I configured the low latency PHY with 8000mbps and 500 MHz and it works without problems.   I changed the refclk to 500 MHz in Qsys/clocks, Qsys/phy and in the sdc-file and of cause i changed the clock on the board.   Does anyone has an idea why some datarates doesn't work, respectivly what I forgot?  Thanks, Micha

[Altera_Forum]

It sound weird, the higher rate works fine while lower rate seems problematic. You mentoned it does not work in external loopbavk, how about internal loopback? 

Question: thd first attempt is work on custom phy or native phy? can try the non-working rate on low latency phy as seem low latency phy is alqays working?

[Altera_Forum]

--- Quote Start ---  It sound weird, the higher rate works fine while lower rate seems problematic. You mentoned it does not work in external loopbavk, how about internal loopback?  --- Quote End ---    i will take a look.    --- Quote Start ---    Question: thd first attempt is work on custom phy or native phy? can try the non-working rate on low latency phy as seem low latency phy is alqays working?  --- Quote End ---    All rates are made on low latency phy. So, I can't follow you exactly, can you give me some more explainations :)?

[Altera_Forum]

Ok, if all on low latency phy, then it is fine. I though u try on different phy. I am trying to isolate the common failure symptom from your experiments

[Altera_Forum]

Maybe u can try the 6gbps using Native Phy, to isolate whether is phy dependent.