TP-Link TD-W8970 & ZTE MF833V usb dongle - Crash

Installing and Using OpenWrt
1

Hi there,

I've got a question. I am using OpenWRT version 18.06.4 r7808-ef686b7292 (kernel: 4.9.184) with an TD-W8970 xRX200 rev 1.2. I have to use the ZTE MF833V as a DHCP client because all attempts to use it as modem didn't work and so I just get the internet connection from the USB dongle as DHCP client and the router distributes it. So far so good... I have experienced a lot of crashes when downloading stuff from other computers.

LSUSB -T gives me following:

/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=dwc2/1p, 480M
    |__ Port 1: Dev 3, If 0, Class=Communications, Driver=cdc_ether, 480M
    |__ Port 1: Dev 3, If 1, Class=CDC Data, Driver=cdc_ether, 480M
    |__ Port 1: Dev 3, If 2, Class=Mass Storage, Driver=usb-storage, 480M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=dwc2/1p, 480M
    |__ Port 1: Dev 2, If 0, Class=Mass Storage, Driver=usb-storage, 480M

I'm writing the logs on a USB stick, so that I can troubleshoot what's going on. The kernel log says following:

Oct 14 12:18:52 OpenWrt kernel: [  233.033372] dwc2 1e106000.ifxhcd: hcint 0x00000002, intsts 0x04600029
Oct 14 12:18:52 OpenWrt kernel: [  233.039806] dwc2 1e106000.ifxhcd: dwc2_update_urb_state_abn(): trimming xfer length
Oct 14 12:18:52 OpenWrt kernel: [  233.047662] dwc2 1e106000.ifxhcd: dwc2_update_urb_state(): trimming xfer length
Oct 14 12:18:56 OpenWrt kernel: [  236.252159] dwc2 1e106000.ifxhcd: dwc2_hc_chhltd_intr_dma: Channel 1 - ChHltd set, but reason is unknown
Oct 14 12:18:56 OpenWrt kernel: [  236.260208] dwc2 1e106000.ifxhcd: hcint 0x00000002, intsts 0x04600029
Oct 14 12:18:56 OpenWrt kernel: [  236.266643] dwc2 1e106000.ifxhcd: dwc2_update_urb_state_abn(): trimming xfer length
Oct 14 12:18:56 OpenWrt kernel: [  236.274513] dwc2 1e106000.ifxhcd: dwc2_update_urb_state(): trimming xfer length
Oct 14 12:19:01 OpenWrt kernel: [  241.371107] dwc2 1e106000.ifxhcd: dwc2_hc_chhltd_intr_dma: Channel 5 - ChHltd set, but reason is unknown
Oct 14 12:19:01 OpenWrt kernel: [  241.379169] dwc2 1e106000.ifxhcd: hcint 0x00000002, intsts 0x04600029
Oct 14 12:19:01 OpenWrt kernel: [  241.385603] dwc2 1e106000.ifxhcd: dwc2_update_urb_state_abn(): trimming xfer length
Oct 14 12:19:01 OpenWrt kernel: [  241.393406] dwc2 1e106000.ifxhcd: dwc2_update_urb_state(): trimming xfer length

And dmesg and other logs aren't saying more that seems helpful for me. But it might be helpful for you guys. Could anybody please help me? The crashes are really annoying... Thanks!

2

Try a powered USB hub

3

Update: Made a stress test with avg load above 10 and cpu load of 97%+ and the router didn't crash. But immediately when I started to download/upload the router crashed. The only process that has had a high load while downloading/uploading is ksoftirqd.

@jeff Sadly I don't have a powered USB hub. Do you think it has to do with that the router doesn't provide enough energy to the USB modem?

4

Given that the modem's connection fails under load (when it is probably transmitting and consuming more power), that would be the first thing I would check.

5

Yeah, but it's only crashing while under network load, not when under CPU load. Isn't that strange?

6

Not at all. The modem likely gets enough power when it is not running its transmitter with a high duty cycle, then fails once you start loading it.

7

So, I tried it with a powered USB hub. Same problem as before, nothing changed, crashing when downloading/uploading.

In addition to above message when the router is booting also this shows up:

[   33.194435] cdc_ether 2-1.1:1.0 usb0: kevent 12 may have been dropped
[   33.199742] cdc_ether 2-1.1:1.0 usb0: kevent 12 may have been dropped
[   33.206135] cdc_ether 2-1.1:1.0 usb0: kevent 12 may have been dropped
[   33.212512] cdc_ether 2-1.1:1.0 usb0: kevent 12 may have been dropped

Anybody has any clue?