Comment 85 for bug 1492764

Happens to me also. After an Ubuntu Update yesterday (2015/02/05), my wifi stopped working and this message started appearing in DMESG:

[ 3191.808441] ahci 0000:00:1f.2: port does not support device sleep
[ 3470.201625] [drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in ips_enabled (expected 1, found 0)
[ 3470.201635] ------------[ cut here ]------------
[ 3470.201684] WARNING: CPU: 0 PID: 779 at /build/linux-NgsOGa/linux-4.2.0/drivers/gpu/drm/i915/intel_display.c:12328 check_crtc_state+0x2c5/0x440 [i915]()
[ 3470.201688] pipe state doesn't match!
[ 3470.201690] Modules linked in: nls_utf8 isofs drbg ansi_cprng ctr ccm rtl8192cu rtl_usb rtl8192c_common rtlwifi uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_core v4l2_common hid_multitouch hid_generic videodev media usbhid nvram msr arc4 nls_iso8859_1 asus_nb_wmi asus_wmi sparse_keymap wl(POE) intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm iwlmvm crct10dif_pclmul mac80211 crc32_pclmul aesni_intel aes_x86_64 lrw gf128mul iwlwifi glue_helper snd_hda_codec_hdmi ablk_helper cryptd input_leds joydev cfg80211 snd_hda_codec_realtek serio_raw snd_hda_codec_generic lpc_ich shpchp mei_me mei snd_hda_intel snd_hda_codec snd_soc_rt5640 snd_hda_core snd_soc_rl6231 snd_hwdep snd_soc_core snd_compress ac97_bus snd_pcm_dmaengine snd_pcm snd_seq_midi snd_seq_midi_event snd_rawmidi
[ 3470.201782] snd_seq snd_seq_device snd_timer snd soundcore int3402_thermal dw_dmac 8250_dw dw_dmac_core i2c_designware_platform processor_thermal_device snd_soc_sst_acpi i2c_designware_core int340x_thermal_zone int3400_thermal spi_pxa2xx_platform acpi_thermal_rel intel_soc_dts_iosf intel_smartconnect mac_hid parport_pc ppdev lp parport autofs4 uas usb_storage psmouse i915 i2c_algo_bit drm_kms_helper drm ahci libahci wmi sdhci_acpi video sdhci i2c_hid hid
[ 3470.201835] CPU: 0 PID: 779 Comm: Xorg Tainted: P W OE 4.2.0-27-generic #32-Ubuntu
[ 3470.201839] Hardware name: ASUSTeK COMPUTER INC. UX301LAA/UX301LAA, BIOS UX301LAA.211 06/05/2015
[ 3470.201842] 0000000000000000 0000000076e06d8c ffff8800d924f7c8 ffffffff817eae99
[ 3470.201849] 0000000000000000 ffff8800d924f820 ffff8800d924f808 ffffffff8107b9c6
[ 3470.201854] ffff8800d924f848 ffff8800d924f8b0 ffff8802110a9800 0000000000000001
[ 3470.201861] Call Trace:
[ 3470.201873] [<ffffffff817eae99>] dump_stack+0x45/0x57
[ 3470.201883] [<ffffffff8107b9c6>] warn_slowpath_common+0x86/0xc0
[ 3470.201889] [<ffffffff8107ba55>] warn_slowpath_fmt+0x55/0x70
[ 3470.201936] [<ffffffffc01909e1>] ? intel_pipe_config_compare+0xb31/0xc60 [i915]
[ 3470.201972] [<ffffffffc0190dd5>] check_crtc_state+0x2c5/0x440 [i915]
[ 3470.202014] [<ffffffffc01a4bfd>] intel_modeset_check_state+0x21d/0x6d0 [i915]
[ 3470.202052] [<ffffffffc01a5db7>] intel_crtc_set_config+0x4c7/0x580 [i915]
[ 3470.202088] [<ffffffffc0096ef5>] ? drm_mode_create+0x25/0x60 [drm]
[ 3470.202115] [<ffffffffc00904a6>] drm_mode_set_config_internal+0x66/0x100 [drm]
[ 3470.202142] [<ffffffffc0094b39>] drm_mode_setcrtc+0x3e9/0x500 [drm]
[ 3470.202160] [<ffffffffc0085495>] drm_ioctl+0x125/0x610 [drm]
[ 3470.202167] [<ffffffff811bf301>] ? page_add_file_rmap+0x51/0x60
[ 3470.202191] [<ffffffffc0094750>] ? drm_mode_setplane+0x1b0/0x1b0 [drm]
[ 3470.202200] [<ffffffff812110b5>] do_vfs_ioctl+0x295/0x480
[ 3470.202208] [<ffffffff810885e1>] ? __set_task_blocked+0x41/0xa0
[ 3470.202214] [<ffffffff81211319>] SyS_ioctl+0x79/0x90
[ 3470.202220] [<ffffffff817f1c72>] entry_SYSCALL_64_fastpath+0x16/0x75
[ 3470.202224] ---[ end trace 468b83e008c9f4b0 ]---
[ 3552.414664] ahci 0000:00:1f.2: port does not support device sleep

Computer: Asus UX301LA, Ubuntu 15.10 fully updated.
I am now using a wifi-dongle because the onboard wifi doesn't work anymore :) (not even with a livecd)