Quoting Douglas Anderson (2022-02-02 13:23:43) > I believe that the PCIe clkreq pin is an output. That means we > shouldn't have a pull enabled for it. Turn it off. It sounds like it's a request from the PCI device to the PCI phy that the clk should be on. I googled pcie clkreq open drain and this pdf[1] says "The CLKREQ# signal is an open drain, active low signal that is driven low by the PCI Express M.2 add-I Card function to request that the PCI Express reference clock be available (active clock state) in order to allow the PCI Express interface to send/receive data" so presumably if there isn't an external pull on the signal the open drain feature will not work and the PCIe device won't be able to drive it low. [1] https://advdownload.advantech.com/productfile/PIS/96FD80-P512-LIS/Product%20-%20Datasheet/96FD80-P512-LIS_datasheet20180110154919.pdf
