I'm having a bit of a hard time understanding the minimal requirements for the CHDR Crossbar and connectivity.
I'm working with an X440, so I have 3 transport adapters (int0, sfp0, sfp1), 2 blocks (radio0, radio1), 2 TX endpoints each with 4 ports (tx0, tx1), and 8 RX endpoints each with 1 port (rx[0-7]). I have tx0 ctrlport enabled, and none of the other ctrlports are enabled. I know I want rx[0-3] to only ever stream out of sfp0, and I want rx[4-7] to only ever stream out of sfp1. I want tx0 and tx1 to both receive CHDR packets from sfp0 and sfp1. I will always configure the device via int0. I also notice that rfnoc_core_kernel has a parameter for CHDR_XBAR_PRESENT. The comment for the parameter states: "1 if the CHDR crossbar is present. If 0 then transports are directly connected to SEPs". Connecting everything through the crossbar even with a sparse routing matrix ends up with around 18kLUT utilization. Since I know I want this extremely fixed and rigid design, I've got some questions: - How much of the CHDR crossbar can I remove? Can I get rid of it altogether? Are there any examples of a design with no CHDR crossbar? - Can I combine the RX SEPs into a single port per SFP connection using an AXI-Streaming mux of some type? Or is this accomplished in the same way in the crossbar with a sparse routing matrix? - How would one connect the multiple SEPs directly to the TA without going through the crossbar as the CHDR_XBAR_PRESENT parameter suggests is possible? Is it possible to describe this in the yaml file or does it require hand editing the generated rfnoc_image_core.sv file? - Since configuration is happening from int0, and tx0 is the only SEP with a ctrlport on it, does this suggest I need int0 to only be connected to tx0 in the connections and it doesn't need to go anywhere else? I will note that I tried this and I received a message saying a route couldn't be found for my remote streams. Is this maybe an oversight with remote streaming and sparse connectivity in the crossbar? I appreciate any insights you might be able to give. Thanks, Brian
_______________________________________________ USRP-users mailing list -- [email protected] To unsubscribe send an email to [email protected]
