(solved) Alfa AWUS036ACM (MediaTek MT7612U Chipset) AP Crashes in OpenWrt

[amisix]

Adapter: Alfa AWUS036ACM (mt7612u) System: Raspberry Pi 4B Rev. 1.5 OS: OpenWrt 21.02.1 (Linux RPi4 5.4.154 aarch64 GNU/Linux) Driver(s): kmod-mt76x2u

Issue: When connected via USB 3.0 adapter crashes after having any appreciable load applied (within a few seconds to a couple minutes). Issue persists after reboot, adapter will not register properly unless power is completely removed from the adapter/Raspberry Pi during reboot process.

Solution: Disable USB Scatter-Gather at startup.

Syslog at the time of crash:

kern.err kernel: [TIME] mt76x2u [USB BUS/PORT]: error: mt76x02u_mcu_wait_resp failed with -110

Kernel log after restart without full poweroff process completed:

usb 2-2.4: reset SuperSpeed Gen 1 USB device number 5 using xhci_hcd
mt76x2u 2-2.4:1.0: ASIC revision: 76120044
mt76x2u 2-2.4:1.0: ROM patch build: 20141115060606a
mt76x2u 2-2.4:1.0: firmware upload failed: -110
mt76x2u: probe of 2-2.4:1.0 failed with error -5
usbcore: registered new interface driver mt76x2u

Solution: Disable USB Scatter-Gather at startup.

Add "mt76-usb disable_usb_sg=1" to /etc/modules.d/mymoduleparam.conf

nano /etc/modules.d/mymoduleparam.conf
mt76-usb disable_usb_sg=1

Ctrl + O to save, Ctrl + X to exit Then reboot

Verify it worked:

cat /sys/module/mt76_usb/parameters/disable_usb_sg

Should be "Y"

[morrownr]

Thank you very much for posting the solution as I am sure there will be others that run into this issue.

Regards

[amisix]

You're welcome. You've put lots of effort into this site. Thank you for your write-up here regarding USB scatter-gather with additional details here.

[morrownr]

Hey @amisix

Did you make a couple of typos in your post above?

---

How to Disable USB Scatter-Gather (mt7612u driver)

sudo nano /etc/modprobe.d/mt76_usb.conf

add the following line:

options mt76_usb disable_usb_sg=1

ctrl + o to save and ctrl + x to exit

sudo reboot

To check:

grep [[:alnum:]] /sys/module/mt76_usb/parameters/*

[amisix]

I thought so too, but for reference: https://github.com/openwrt/mt76/issues/405#issuecomment-1030740067

There is no sudo/no need for sudo in OpenWrt (depending if config is different than default I guess?) There is no /etc/modprobe.d directory in OpenWrt. Apparently it's equivalent is /etc/modules.d ? Since there is no /etc/modprobe.d/ there is no m76_usb.conf. But I was kind of using @bjlockie 's instructions because I hadn't found yours yet. Where bjlockie said to use /etc/modprobe.d/mymoduleparam.conf. But there is no /etc/modprobe.d/ directory and no mymoduleparam.conf.

So I modified it to /etc/modules.d/mymoduleparam.conf and it works fine. I tried to follow the directions as written by others but that's what I ran into while configuring it. Am able to run the check command after restart and it's "Y".

I don't mean to butcher yours or anyone else's instructions. If you'd like me to modify some way, I'll edit as necessary.

[Echo522-prog]

I need help, so I have the AWUS036ACM well I try and use the rtl8812au chipset but It doesn't work and even when I use the lsusb command the adapter Doesn't show up.

[morrownr]

I need help, so I have the AWUS036ACM well I try and use the rtl8812au chipset but It doesn't work and even when I use the lsusb command the adapter Doesn't show up.

Hi @Echo522-prog

Can I get you to open a new issue and include some information such as a brief description of your computer hardware and operating system as well as what you are trying to do? Thanks.

I try and use the rtl8812au chipset

I don't understand this comment. The Alfa ACM uses a mt7612u chipset.

Regards