IPQ4019 xhci-hcd host died - modem crashing?

[bmork]

@biangbiangmian

I am testing a Unielec U4019-01 and running into some crashes. I am testing with a Sierra Wireless EM7565 in conjunction with ModemManager, tested in MBIM ( 1,3,1009 ) and QMI ( 1,3,10D ) mode. I am using a NGFF to mPCIe adaptor. The rest of this post is my logs, and list of things I have tried.

This made me curious about the NGFF to mPCIe adaptor. Is this a special adapter intended for mPCIe slots with the USB3 SS pairs, or just an arbitrary one intended for mPCIe slots with the usuaul PCIe pairs connected to those pins?

Note the the EM7365 supports PCIe connections as well as USB2 and USB3, in theory at least. So a normal NGFF-adapter will likely cause problems by connecting the host USB3 pins to the modem PCIe pins

@biangbiangmian

I have attempted to access the modem over USB2 mode, but this is a little difficult as the mPCIe slot is connected to the SoC's USB3 pins. I may attempt to tape over the USB 3.0 pins on the adaptor or modem and test again.

Did you try this? If the problem is what I suspect, then taping over the USB3 pins will fix it. I believe the USB2 pins should be connected. Looking at pictures of the U4019 shows 3 differential pairs leading to the mPCIe slot.

It would be really nice to be able to use USB3 with this router though. I don't understand why they made it with a mPCIe slot instead of an m.2 slot. It would have been so much more useful with m.2. I guess mPCIe modems like the MC7455 will work fine with USB3 here. But those are old and rare, and not as fast as the EM7565.