Måns Rullgård <mans@xxxxxxxxx> writes: > Dan Williams <dcbw@xxxxxxxxxx> writes: > >> TLDR; some firmware uses the DTR signal as an indicator to come out of >> low-power mode. Without doing so you cannot talk to the modem over any >> of it's ports, QMI, net, or serial. > > I must be missing something, but how does a network interface have a DTR > signal? It does not. But the network function is (ab)using the Comm class USB control message "SetControlLineState" to signal "wake up" from the host to the device. Which is perfectly fine since the USB function in question is vendor specific. The vendor can define any USB control message to mean anything they want. Reusing a Comm class message probably made sense to the firmware engineer designing this. We can only note and adapt. It doesn't have anything to do with DTR. Bjørn
