Quectel EP06 modem "transaction timed out" lockup

Fri Aug 28 17:54:23 UTC 2020

Yes, I see the following error:

  ------------[ cut here ]------------
[773624.684162] WARNING: CPU: 0 PID: 0 at net/sched/sch_generic.c:320 
dev_watchdog+0x16c/0x24
8
[773624.687801] NETDEV WATCHDOG: wwan0 (qmi_wwan): transmit queue 0 
timed out
[773624.696031] Modules linked in: qcserial ppp_async option cdc_mbim 
batman_adv ath10k_pci a
th10k_core ath usb_wwan sierra_net sierra qmi_wwan ppp_generic pl2303 
nf_conntrack_ipv6 mac80
211 iptable_nat ipt_REJECT ipt_MASQUERADE ftdi_sio ebtable_nat 
ebtable_filter ebtable_broute
ch341 cfg80211 cdc_ncm xt_time xt_tcpudp xt_state xt_nat xt_multiport 
xt_mark xt_mac xt_limit
  xt_conntrack xt_comment xt_TCPMSS xt_REDIRECT xt_LOG xt_FLOWOFFLOAD 
usbserial usbnet slhc nf
_reject_ipv4 nf_nat_redirect nf_nat_masquerade_ipv4 nf_conntrack_ipv4 
nf_nat_ipv4 nf_nat nf_l
og_ipv4 nf_flow_table_hw nf_flow_table nf_defrag_ipv6 nf_defrag_ipv4 
nf_conntrack_rtcache nf_
conntrack macvlan libcrc32c iptable_mangle iptable_filter ip_tables 
ebtables ebt_vlan ebt_stp
  ebt_redirect ebt_pkttype ebt_mark_m ebt_mark ebt_limit ebt_ip6 ebt_among
[773624.751846]  ebt_802_3 crc_ccitt compat cdc_wdm cdc_acm act_skbedit 
act_mirred em_u32 cls
_u32 cls_tcindex cls_flow cls_route cls_fw sch_tbf sch_htb sch_hfsc 
sch_ingress sg xt_set ip_
set_list_set ip_set_hash_netiface ip_set_hash_netport ip_set_hash_netnet 
ip_set_hash_net ip_s
et_hash_netportnet ip_set_hash_mac ip_set_hash_ipportnet 
ip_set_hash_ipportip ip_set_hash_ipp
ort ip_set_hash_ipmark ip_set_hash_ip ip_set_bitmap_port 
ip_set_bitmap_ipmac ip_set_bitmap_ip
  ip_set nfnetlink ip6t_REJECT nf_reject_ipv6 nf_log_ipv6 nf_log_common 
ip6table_mangle ip6tab
le_filter ip6_tables x_tables dummy ip6_tunnel tunnel6 tun autofs4 
usb_storage leds_gpio xhci
_plat_hcd xhci_pci xhci_hcd dwc3 dwc3_of_simple ahci libahci libata 
ehci_platform sd_mod scsi
_mod ehci_hcd ext4 jbd2 mbcache mii crc32c_generic
[773624.820884] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.171 #0
[773624.843017] Hardware name: Generic DT based system
[773624.849280] [<c030eeac>] (unwind_backtrace) from [<c030afe8>] 
(show_stack+0x10/0x14)
[773624.854049] [<c030afe8>] (show_stack) from [<c07659b4>] 
(dump_stack+0x94/0xa8)
[773624.862036] [<c07659b4>] (dump_stack) from [<c0321dfc>] 
(__warn+0xe8/0x104)
[773624.869148] [<c0321dfc>] (__warn) from [<c0321e50>] 
(warn_slowpath_fmt+0x38/0x48)
[773624.876441] [<c0321e50>] (warn_slowpath_fmt) from [<c0699134>] 
(dev_watchdog+0x16c/0x248)
[773624.883817] [<c0699134>] (dev_watchdog) from [<c03728f0>] 
(call_timer_fn+0x98/0x17c)
[773624.892083] [<c03728f0>] (call_timer_fn) from [<c0372af0>] 
(expire_timers+0x11c/0x134)
[773624.899991] [<c0372af0>] (expire_timers) from [<c0372b7c>] 
(run_timer_softirq+0x74/0x180)
[773624.907775] [<c0372b7c>] (run_timer_softirq) from [<c03015a4>] 
(__do_softirq+0x164/0x338)
[773624.916109] [<c03015a4>] (__do_softirq) from [<c0326928>] 
(irq_exit+0xd4/0x138)
[773624.924356] [<c0326928>] (irq_exit) from [<c0360c34>] 
(__handle_domain_irq+0x9c/0xac)
[773624.931906] [<c0360c34>] (__handle_domain_irq) from [<c030140c>] 
(gic_handle_irq+0x5c/0x9
0)
[773624.939632] [<c030140c>] (gic_handle_irq) from [<c030bb4c>] 
(__irq_svc+0x6c/0x90)
[773624.948211] Exception stack(0xc0a01f40 to 0xc0a01f88)
[773624.955592] 1f40: 00000001 00000000 00000000 c03144a0 ffffe000 
c0a03cf8 c0a03cac 00000000
[773624.960716] 1f60: 00000000 00000001 cfffce00 c093ca28 c0a01f88 
c0a01f90 c0308148 c030814c
[773624.968981] 1f80: 60000013 ffffffff
[773624.977228] [<c030bb4c>] (__irq_svc) from [<c030814c>] 
(arch_cpu_idle+0x34/0x38)
[773624.980962] [<c030814c>] (arch_cpu_idle) from [<c0357408>] 
(do_idle+0xdc/0x1a0)
[773624.988332] [<c0357408>] (do_idle) from [<c0357728>] 
(cpu_startup_entry+0x18/0x1c)
[773624.995802] [<c0357728>] (cpu_startup_entry) from [<c0900c88>] 
(start_kernel+0x3c0/0x3cc)
[773625.003365] ---[ end trace 22c29886c4a23e83 ]---

On 2020-08-28 01:27, tschaefer at t-online.de wrote:
> Have seen kernel message with dmesg during the problem occurs?
> 
> Am 28.08.2020 02:43 schrieb Alex Ballmer <alexb at meshplusplus.com>:
> 
>     I have a series of Quectel EP06 modems that occasionally experience a
>     deadlock condition. I am running openwrt 18.06.8 using modemmanager
>     1.14.0 and libqmi 1.26.2.
> 
> 
>     After being online for some time, the modems will eventually lose the
>     ability to ping. mmlci still shows the same bearer as when it was
>     working. Netifd does not show wwan0 (the network interface for that
>     modem) as having an address.
> 
>     Attempting to reset the modem via mmcli returns
> 
>     error: couldn't reset the modem:
>     'GDBus.Error:org.freedesktop.libqmi.Error.Core.Timeout: Transaction
>     timed out'
> 
> 
>     Resetting via AT commands (echo -ne "AT+CFUN=1,1\r\n" > /dev/ttyUSB3)
>     does not result in any response from the modem. Rebooting the affected
>     machine causes the modem to function normally again.
> 
>     It should be noted that when the modem enters this state, mmcli still
>     reports it as being connected.
> 
>     Is this an issue with the modem itself or something that can be worked
>     around in software?
> 
>     Thanks
>     _______________________________________________
>     libqmi-devel mailing list
>     libqmi-devel at lists.freedesktop.org
>     https://lists.freedesktop.org/mailman/listinfo/libqmi-devel
> 
> 