Yegor Yefremov wrote: > Hi Craig, > > On Tue, May 10, 2016 at 8:08 AM, Craig McQueen > <craig.mcqueen@xxxxxxxxxxxxxx> wrote: > > I previously wrote: > >> I previously wrote: > >> > I previously wrote: > >> > > > >> > > I have a D-Link DWA-140 USB Wi-Fi device which is rt2800 based > >> > > (5392 chipset). I've been testing it on a BeagleBone Black > >> > > running an Ubuntu > >> > > 16.04 image (4.4.6 kernel), with a USB hub. > >> > > > >> > > When I unplug the Wi-Fi device from the USB hub, and it's > >> > > connected to an access point, and then I unplug it, the OS appears to > lock up. > >> > > I get messages about a soft lockup on the serial console: > >> > > > >> > > [ 9736.136702] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! > >> > > [kworker/u2:0:1129] [ 9764.136701] NMI watchdog: BUG: soft lockup > >> > > - > >> > > CPU#0 stuck for 22s! [kworker/u2:0:1129] [ 9792.136701] NMI > watchdog: > >> > > BUG: soft lockup - CPU#0 stuck for 22s! [kworker/u2:0:1129] [ > >> > > 9820.136699] NMI > >> > > watchdog: BUG: soft lockup - CPU#0 stuck for 22s! > >> > > [kworker/u2:0:1129] [ 9848.136696] NMI watchdog: BUG: soft lockup > >> > > - > >> CPU#0 stuck for 22s! > >> > > [kworker/u2:0:1129] > >> > > > >> > > This will repeat indefinitely, until I unplug the hub, which > >> > > resolves the soft lockup and then the system seems to function > normally. > >> > > > >> > > I've attached a dmesg log of the soft lockup stack traces. They > >> > > seem to indicate a lockup in workqueue rt2x00usb_work_rxdone() > >> > > (specifically in > >> > > usb_hcd_submit_urb() called from rt2x00usb_kick_rx_entry() called > >> > > from rt2x00usb_clear_entry()). > >> > > > >> > > I originally found this bug on a 3.14.x kernel built with Yocto > >> > > for a BeagleBone Black-based product. So it seems this is a bug > >> > > that has been around for some time. > >> > > >> > I should also note that on the 3.14.x Yocto-built kernel on > >> > BeagleBone Black, this bug does not occur if the rt2800 device is > >> > unplugged directly from the BBB's USB port. It only occurs if unplugged > from a hub. > >> > > >> > I have tested this on an i586 based eBox-3310A mini-PC running > >> > Debian 8.4, which has a 3.16.0 kernel, with the same hub and same > >> > rt2800 device. But I was not able to reproduce this issue. > >> > >> There is a patch for the AM335x musb driver that seems to fix this: > >> > >> http://marc.info/?l=linux-usb&m=146173995117456&w=2 > >> > >> So it seems that this issue's root cause is in the AM335x USB > >> interrupt handling, and not the Wi-Fi rt2800 driver. > > > > Having applied two AM335x USB patches in the 3.14.49 kernel, that does > seem to resolve the soft lock-up on the RX side. The two patches are: > > > > http://marc.info/?l=linux-usb&m=146173995117456&w=2 > > http://marc.info/?l=linux-usb&m=146222355213935&w=2 > > > > But I am finding there is still a lock-up issue when unplugging from a hub, > this time on the TX side. It is more likely if there is Wi-Fi traffic in progress > when the unplug occurs. I'm attaching a log. Essentially there are a heap of > lines (100 or so per second): > > > > [ 1866.693511] ieee80211 phy7: rt2800usb_tx_sta_fifo_read_completed: > > Warning - TX status read failed -71 > > > > Which finally stop shortly after USB disconnect is detected: > > > > [ 1866.985854] usb 1-1.3: USB disconnect, device number 10 > > > > However that disconnect message is typically 30-90 seconds after the > unplug happened. It seems that the USB disconnect detection is delayed due > to the CPU load of the TX. > > > > I also sometimes see a kernel panic. That can occur whether connected to a > USB hub or directly to the on-board USB port. See the attached log. > > > > I'm not so familiar with either the Wi-Fi or USB stacks in the Linux > > kernel, so I would appreciate any advice with debugging and fixing > > this. (My previous investigations indicate these issues are present in > > both 3.14.x kernel and 4.4.6 kernel. I'm more familiar with working > > with the 3.14.x kernel under Yocto, but I could try moving to 4.4.6 > > kernel for Ubuntu. I'm open to advice on which to investigate on.) > > Take a look at this patch: http://marc.info/?l=linux- > usb&m=146222355213935&w=2 > > If it fixes your issue please provide your "tested-by" tag here. Hi Yegor, I am using that patch, and I referred to it in my last message. But it doesn't fix this issue. Thanks, Craig McQueen ��.n��������+%������w��{.n�����{���zW����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
