How to remove the Unused_RX_Clock_Workaround_PMR_CDR_PLL which inserted by Quartus Prime fitter ?

[KJian6]

Hi,

I have a FPGA system which include both DDR4 IP and USB3 controller. The Quartus prime 18.1 build 222 has inserted lots of  Unused_RX_Clock_Workaround_PMR_CDR_PLL during place&route:

UNUSED_RX_CLOCK_WORKAROUND_FITTER_INSERTED_PMA_CDR_PLL0 :

Location :       HSSIPMACDRPLL_1C0          

  datarate           ; 1.0 ms

output_clock_frequency    ; 2.9 ms                                

reference_clock_frequency  ; 100us                              

vco_freq           ; 8.0ms                                                       

...............

How to get rid of these UNUSED_WORKAROUND PLLs?

Thanks!

[NurAida_A_Intel]

Dear KJian6,

Based on my understanding, you are referring to “Transmitter PLL” in the GXB Report.

To get rid of these unused PLLs you need to turn OFF the “ENABLE_UNUSED_RX_CLOCK_WORKAROUND ON” in your .QSF as below and re-compile your project.

set_global_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND OFF

set_instance_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND OFF -to <pin name>

After compilation, you should able to see the Total PLLs number decrease and there is no Transmitter PLL generated in your Fitter report.

I sincerely hope this helps.

Thanks

Regards,

NAli1

[NurAida_A_Intel]

posted a file.

[KJian6]

Hi Nali1:

Many thanks for your help!

However, I have tried to add the command "set_global_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND OFF" only in the QSF firstly.

It didn't work and those "Transmitter PLL" are still there.

For another command "set_instance_assignment -name ENABLE_UNUSED_RX_CLOCK_WORKAROUND OFF -to <pin name>",

I don't know which pin name should be assigned here ? How to find the related "Pin Name" from the output log file ?

Would you kindly give me some guide ?

Thanks again,

KJian6

[NurAida_A_Intel]

Dear KJian6,

I have tried the command in my DDR4 example design and its work. The Fitter successfully generated without any “Transmitter PLLs”. I attached together my .QAR example design for your reference.

You can see in my .QSF (line 190 and 191) which I turn OFF the “ENABLE_UNUSED_RX_CLOCK_WORKAROUND”. Please also note that you need to add both of the command in your .QSF before compilation. For the <pin name>, its actually depend on your design. I recommend you to try the pin that fit into your design.

Hope this helps.

Thanks

Regards

NAli1