Erroneous DDR4 warning that max allowed frequency is 1066 on XCZU19EG-FFVB1517 FPGA

[mosaix]

I am using Vivado 2018.3 and targeting a Zynq UltraScale+ XCZU19EG-FFVB1517-1 device.

In setting up the DDR4 PS configuration, I am getting the following waring message:

[PSU-1] Current DDR actual interface frequency is : 1199.988 . According to Datasheet DS925 maximum allowed interface frequency value for current part is : 1066.000 .

According to the DS925 datasheet, this warning is incorrect. For the FFVB package, the max allowed frequency is 2400.

Looks like a bug in Vivado 2018.3.

[gnarahar]

@mosaix  Can you share your expanded Clock Configuration (Input and Output clock tabs) and DDR configurtaion settings screenshot.

[mosaix]

As you requested, I have attached the screeen shots for the clk as well as DDR settings. Also included is a tcl file to re-create the zynq processor settings I am using as well as the error warning.

One thing to note. When using Vivado 2018.2, I did not encounter this issue. 

When I migrated to Vivado 2018.3, that is wehn I ran into this DDR4 warning

[gnarahar]

@mosaix  Thank you for sharing your settings. As I was suspecting, you are using DIMM and so the warning shows up which is inline with the datasheet. For DIMM's the Max speed is reduced compared to Component as seen below. 

[mosaix]

I am confused.Here is why:

1. If I use Vivado 2018.3;  target the ZCU104 board; instantiate the Zynq processor; and apply board presets; then I am able to run the DDR4 memory at 1067 MHz for DDR4 UDIMM memory. No error messages are flagged. See the attached ZCU104 clok and memory configuration screen capture.

2. If i taget my custom board, then the max frequency I am allowed to enter for the DDR4 memory with no errors is 800 MHz. Anything other frequency flags errors in 2018.3. I did not have this issue when using 2018.2

Would appreciate your explanation of what is going on.

[mosaix]

I meant the ZCU102 board in the previous message and *not* the ZCU104.

[gnarahar]

@mosaix  When you say target custom board, you mean you selected a MPSoC Device (that's on your board and mentioned in title) in Vivado and building a design or built a board XML file to have your custom board show up in Vivado and choosing that (like ZCU102) in Vivado? 

Can you share the settings in which you hit the warning for 800MHz?

Regarding the change in 2018.3 and 2018.2, I suspect the check may have been added in 2018.3 and so you see the warning when you set the frequency out of range for the specific device/speedgrade. Once I see youe settings, will try checking at my end and see what i get. 

[mosaix]

I have attached two separate pdf files showing clock and DDR cconfigurations for tow separate board. The first board is the Xilinx ZCU102 board and the second board is a custom board that uses a Zynq Ultrascale as well.

Please note that on the Zynq Ultrascale+ processor on the ZCU102 board (using board presets in Vivado to configure the board), the requested and  actual device frequency are both set to 1067 MHz when configured for DDR4 2133P

When I configure the Zynq Ultrascale+ for my custom board (i.e. without the use of board presets), I am also requesting 1067 MHz device frequency  for DDR4 2133P, however the Vivado tool only allows an "actual device frequency" of 799.99 MHz which is a lot less.

Both boards use UDIMMs - so why is the actual device frequency a lot less?