iwlwifi fails with latest firmware

Reproduced on my x220:
ii linux-firmware 1.122 all Firmware for Linux kernel drivers
03:00.0 Network controller: Intel Corporation Centrino Wireless-N 1000 [Condor Peak]
[ 20.552702] iwlwifi 0000:03:00.0: loaded firmware version 39.31.5.1 build 35138 op_mode iwldvm

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[ 2994.296875] iwlwifi 0000:03:00.0: fail to flush all tx fifo queues Q 0
[ 2994.296888] iwlwifi 0000:03:00.0: Current SW read_ptr 11 write_ptr 12
[ 2994.316553] ------------[ cut here ]------------
[ 2994.316592] WARNING: CPU: 2 PID: 15336 at /build/buildd/linux-3.13.0/drivers/net/wireless/iwlwifi/pcie/trans.c:980 iwl_trans_pcie_grab_nic_access+0xcb/0xe0 [iwlwifi]()
[ 2994.316596] Timeout waiting for hardware access (CSR_GP_CNTRL 0xffffffff)
[ 2994.316600] Modules linked in: ctr ccm btusb overlayfs nls_iso8859_1 xt_conntrack ipt_REJECT ip6table_filter ip6_tables ebtable_nat ebtables xt_CHECKSUM iptable_mangle ipt_MASQUERADE iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack xt_tcpudp bridge stp llc iptable_filter ip_tables x_tables parport_pc ppdev rfcomm bnep bluetooth binfmt_misc joydev intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_core arc4 videodev iwldvm mac80211 snd_hda_codec_hdmi thinkpad_acpi nvram microcode snd_hda_codec_conexant snd_seq_midi snd_seq_midi_event snd_rawmidi psmouse serio_raw snd_hda_intel snd_seq snd_hda_codec iwlwifi cfg80211 snd_hwdep lpc_ich snd_pcm snd_seq_device snd_page_alloc snd_timer snd mei_me mei soundcore mac_hid lp parport dm_crypt usb_storage crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel aes_x86_64 i915 lrw gf128mul glue_helper ablk_helper cryptd e1000e i2c_algo_bit drm_kms_helper ptp ahci sdhci_pci pps_core drm libahci sdhci video wmi
[ 2994.316740] CPU: 2 PID: 15336 Comm: kworker/u16:1 Not tainted 3.13.0-5-generic #20-Ubuntu
[ 2994.316745] Hardware name: LENOVO 42872WU/42872WU, BIOS 8DET55WW (1.25 ) 11/01/2011
[ 2994.316787] Workqueue: phy0 ieee80211_beacon_connection_loss_work [mac80211]
[ 2994.316792] 0000000000000009 ffff88009475db98 ffffffff81705069 ffff88009475dbe0
[ 2994.316801] ffff88009475dbd0 ffffffff8106467d ffff880309630000 ffff880309633258
[ 2994.316808] ffff88009475dc78 0000000000000000 0000000000000004 ffff88009475dc30
[ 2994.316815] Call Trace:
[ 2994.316829] [<ffffffff81705069>] dump_stack+0x45/0x56
[ 2994.316840] [<ffffffff8106467d>] warn_slowpath_common+0x7d/0xa0
[ 2994.316848] [<ffffffff810646ec>] warn_slowpath_fmt+0x4c/0x50
[ 2994.316870] [<ffffffffa0347eba>] ? iwl_read32+0x1a/0x80 [iwlwifi]
[ 2994.316888] [<ffffffffa03492ab>] iwl_trans_pcie_grab_nic_access+0xcb/0xe0 [iwlwifi]
[ 2994.316904] [<ffffffffa034a351>] iwl_trans_pcie_read_mem+0x31/0x130 [iwlwifi]
[ 2994.316920] [<ffffffffa034838d>] iwl_trans_pcie_wait_txq_empty+0x15d/0x3e0 [iwlwifi]
[ 2994.316939] [<ffffffffa0501090>] iwlagn_mac_flush+0xa0/0x180 [iwldvm]
[ 2994.316973] [<ffffffffa0460bfd>] ieee80211_flush_queues+0xbd/0x140 [mac80211]
[ 2994.317006] [<ffffffffa0477374>] ieee80211_mgd_probe_ap_send+0xa4/0x140 [mac80211]
[ 2994.317036] [<ffffffffa0474892>] ? ieee80211_cqm_rssi_notify+0x32/0x80 [mac80211]
[ 2994.317064] [<ffffffffa0476f1e>] ? ieee80211_recalc_ps.part.24+0xce/0x200 [mac80211]
[ 2994.317091] [<ffffffffa0477515>] ieee80211_mgd_probe_ap.part.25+0x105/0x160 [mac80211]
[ 2994.317118] [<ffffffffa0477b7d>] ieee80211_beacon_connection_loss_work+0x5d/0x90 [mac80211]
[ 2994.317127] [<ffffffff81080872>] process_one_work+0x182/0x450
[ 2994.317134] [<ffffffff81081611>] worker_thread+0x121/0x410
[ 2994.317142] [<ffffffff810814f0>] ? rescuer_thread+0x3e0/0x3e0
[ 2994.317148] [<ffffffff81088262>] kthread+0xd2/0xf0
[ 2994.317155] [<ffffffff81088190>] ? kthread_create_on_node+0x190/0x190
[ 2994.317164] [<ffffffff8171597c>] ret_from_fork+0x7c/0xb0
[ 2994.317171] [<ffffffff81088190>] ? kthread_create_on_node+0x190/0x190
[ 2994.317175] ---[ end trace 2964175adf3c7828 ]---
[ 2994.317211] iwl data: 00000000: d0 92 7b 09 03 88 ff ff 00 86 7b 09 03 88 ff ff ..{.......{.....
[ 2994.336899] iwlwifi 0000:03:00.0: FH TRBs(0) = 0x5a5a5a5a
[ 2994.356657] iwlwifi 0000:03:00.0: FH TRBs(1) = 0x5a5a5a5a
[ 2994.376374] iwlwifi 0000:03:00.0: FH TRBs(2) = 0x5a5a5a5a
[ 2994.396066] iwlwifi 0000:03:00.0: FH TRBs(3) = 0x5a5a5a5a
[ 2994.415752] iwlwifi 0000:03:00.0: FH TRBs(4) = 0x5a5a5a5a
[ 2994.435437] iwlwifi 0000:03:00.0: FH TRBs(5) = 0x5a5a5a5a
[ 2994.455215] iwlwifi 0000:03:00.0: FH TRBs(6) = 0x5a5a5a5a
[ 2994.474958] iwlwifi 0000:03:00.0: FH TRBs(7) = 0x5a5a5a5a
[ 2994.514336] ------------[ cut here ]------------