Root-endpoint PCIe communication between Xaviers with a bridge in the way

Autonomous Machines Jetson & Embedded Systems Jetson AGX Xavier
4
  1. We don’t have the required cable to directly connect the Xaviers. Do you think the R88SS on this page would be sufficient? R88 PCIe x8 Jumpers Cable It seems that another user on this forum had some success: xavier pcie endpoint mode - #9 by arunas.salkauskas
  2. I could not find a primary source stating that iPass carries REFCLK and PERST#, however this (admittedly different) cable carries PERST# and more (http://cdn.teledynelecroy.com/files/manuals/ipass-connector-to-summit-t4-cable-quick-start-guide.pdf), and this product page lists our type of cable’s pins, including CPERST#, CREFCLK+ and CREFCLK- (External PCIe x4 Cable (iPass 38pin compatible) Cable (CB-00485 / CB-00518) ,745460400, 745460401, 745460402, 745460403, 745460404, 745460405 | CB-00485-A)
  3. The PCIe switch is part of endpoint’s PCIe card, and I have configured it into its “target mode”. I assume this means that it should propagate REFCLK and PERST#, but don’t know for sure.
  4. pex_rst was initially 0, however upon booting up the host Xavier it incremented to 1. Does this imply that the PERST# signal is correctly propagating from the Xavier-RP to Xavier-EP?

Are there any other actions I can take to attempt to debug this issue? Perhaps some way to verify that REFCLK is being propagated as well, in case the presence of PERST# doesn’t necessarily imply that REFCLK is already present?