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FS#2738 - [ramips] dwc2 no longer sees device with 0032-USB-dwc2-add-device_reset.patch #7895

openwrt-bot opened this issue Jan 15, 2020 · 2 comments


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@openwrt-bot openwrt-bot commented Jan 15, 2020


Device: AXIMCom MR-102N
Last known working OpenWrt/LEDE release: lede-17.01

The DWC2 USB controller still probes according to dmesg output; however, the kernel no longer sees any USB device being plugged in.

Step to reproduce:

  1. boot with OpenWrt 18.06 / 19.07 / trunk
  2. insert USB flash disk
  3. /sys/devices/platform/101c0000.otg/usb1/1-1 won't be available, nothing new on dmesg


  1. remove target/linux/ramips/patches-4.14/0032-USB-dwc2-add-device_reset.patch and rebuild kernel
  2. dmesg would show 'usb 1-1: new high-speed USB device number 2 using dwc2' when new USB device is inserted

% dmesg
[ 5.250886] dwc2 101c0000.otg: Configuration mismatch. dr_mode forced to host
[ 5.302541] dwc2 101c0000.otg: DWC OTG Controller
[ 5.312342] dwc2 101c0000.otg: new USB bus registered, assigned bus number 1
[ 5.326774] dwc2 101c0000.otg: irq 26, io mem 0x101c0000

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@openwrt-bot openwrt-bot commented Jan 20, 2020


A quick bisect indicates that the last known working kernel with 0032-USB-dwc2-add-device_reset.patch applied is 4.4.208; however, after switching drivers/usb/dwc2/. to 4.5.0, the device_reset patch will make the device un-discoverable.

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@openwrt-bot openwrt-bot commented May 19, 2020


Confirmed. With the patch removed, USB works fine on 18.06, 19.07 and master.

I recently acquired this little, obscure device "WS-WR512N1" (ramips) and flashed OpenWrt 19.07.3 on it. It worked well, but USB devices would not show up at all. I read a blog post from 2011 where the author of the port says that USB should work, so I tried older releases and sure enough, USB devices would appear on releases up to 17.01.x (kernel 4.4).

I bisected and the breaking commit is [[;a=commit;h=fddc78bc116bc043fb5cd92dbc45cfd054c21af8|ramips: bump to v4.9]].

The dwc2 driver has seen a lot of development between kernels [[|4.4.74]] and [[|4.9.34]] and if 0032-USB-dwc2-add-device_reset.patch is applied on these newer kernels, the driver will be broken.

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