I've also been working with USB QMI modems (Quectel and Simcom) and getting suspend-to-ram/resume working smoothly, so I figured perhaps I can share some of the things I've learnt along the way. But do note that I'm not by any means an expert here - this is my first foray into usb & modems, so do take what I say with a grain of salt.
Firstly, I agree with Aleksander's opinion above - I think the underlying problem is the fact that the USB connection is being reset upon resume. I'd try to solve that first - disable MM & NM altogether for now, and focus on the qmi & usb layers. Use qmicli to set up a connection or at least check basic info with commands like qmicli --device=/dev/cdc-wdm0 --device-open-proxy --dms-get-model Then start looking at the USB side of things. The kernel docs https://www.kernel.org/doc/html/v4.14/driver-api/usb/power-management.html provide some good background info on this area. If I had a pinephone or similar hardware to test with I might be able to provide some more guidance, however I can perhaps shed some light by showing what was required to get my particular device working. My device is an IMX6ULL, and the modem is connected directly to the USB host pins on the chip itself. No USB hub ICs involved. Power to the modem is controlled externally (in my case it's always on). USB info: root@imx6ul-var-dart:~# lsusb -tv /: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ci_hdrc/1p, 480M ID 1d6b:0002 Linux Foundation 2.0 root hub /: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ci_hdrc/1p, 480M ID 1d6b:0002 Linux Foundation 2.0 root hub |__ Port 1: Dev 2, If 0, Class=Vendor Specific Class, Driver=option, 480M ID 2c7c:0125 Quectel Wireless Solutions Co., Ltd. EC25 LTE modem |__ Port 1: Dev 2, If 1, Class=Vendor Specific Class, Driver=option, 480M ID 2c7c:0125 Quectel Wireless Solutions Co., Ltd. EC25 LTE modem |__ Port 1: Dev 2, If 2, Class=Vendor Specific Class, Driver=option, 480M ID 2c7c:0125 Quectel Wireless Solutions Co., Ltd. EC25 LTE modem |__ Port 1: Dev 2, If 3, Class=Vendor Specific Class, Driver=option, 480M ID 2c7c:0125 Quectel Wireless Solutions Co., Ltd. EC25 LTE modem |__ Port 1: Dev 2, If 4, Class=Vendor Specific Class, Driver=qmi_wwan, 480M ID 2c7c:0125 Quectel Wireless Solutions Co., Ltd. EC25 LTE modem The following 3 tweaks are needed to get the modem persisting across a suspend/resume: echo auto > /sys/bus/usb/devices/1-1/power/control echo enabled > /sys/bus/platform/devices/2184000.usb/power/wakeup echo enabled > /sys/bus/platform/devices/ci_hdrc.0/power/wakeup Obviously your USB setup will be different so the above won't work, but perhaps it might provide some direction. The first one - setting control to auto - makes sense to me, but I cannot see why the other two are needed. Having a good poke around the /sys/ tree is a good start anyway - set control=auto and wakeup=enabled on all the usb devices on/above the modem. Finding the equivalent of my 2nd line might be trickier and need some datasheet or device-tree reading to correctly identify it. If you have USB hub devices in the chain then things will be more complex, but I'd be surprised if they've set up the hardware that way. Finally, to allow the modem to wakeup the host, the following two tweaks were needed: echo enabled > /sys/bus/usb/devices/usb1/power/wakeup echo enabled > /sys/bus/usb/devices/1-1/power/wakeup Also, note I'm suspending via the very raw echo mem > /sys/power/state so I can be sure that no setup/teardown is occuring. But obviously pm-suspend or systemctl suspend is the right way to do things for production units. Hopefully that's useful, and best of luck :) Regards, Tom _______________________________________________ ModemManager-devel mailing list ModemManager-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/modemmanager-devel
