What else information is needed?

I have tried with the daily kernel 3.17.0-999.201409272205 and the tainting still occurs. The syslog trace related to suspending event is slightly different (dis_dev_get+0x15/0x40 [bbswitch] instead of pci_bus_read_config_dword+0x64/0x90 in the initial report with kernel 3.13):
[ 3342.022581] init: anacron main process (13582) killed by TERM signal
[ 3342.297888] PM: Syncing filesystems ... done.
[ 3342.489577] PM: Preparing system for mem sleep
[ 3342.489787] general protection fault: 0000 [#1] SMP 
[ 3342.489988] Modules linked in: bbswitch(OE) ip6table_filter ip6_tables iptable_filter ip_tables x_tables snd_hrtimer cuse rfcomm bnep bluetooth binfmt_misc dm_crypt snd_hda_codec_hdmi arc4 ath9k ath9k_common ath9k_hw snd_hda_codec_realtek snd_hda_codec_generic ath snd_hda_intel snd_hda_controller snd_hda_codec mac80211 snd_hwdep uvcvideo snd_pcm videobuf2_vmalloc videobuf2_memops videobuf2_core v4l2_common snd_seq_midi snd_seq_midi_event kvm_intel videodev media snd_rawmidi snd_seq cfg80211 snd_seq_device kvm snd_timer snd parport_pc mxm_wmi ppdev soundcore coretemp joydev lp lpc_ich serio_raw parport mac_hid asus_laptop wmi sparse_keymap input_polldev uas usb_storage psmouse ahci libahci i915 atl1c i2c_algo_bit drm_kms_helper drm video
[ 3342.491087] CPU: 1 PID: 13498 Comm: pm-suspend Tainted: G        W  OE  3.17.0-999-generic #201409272205
[ 3342.491296] Hardware name: ASUSTeK Computer Inc.         UL80VT              /UL80VT    , BIOS 214     01/17/2011
[ 3342.491505] task: ffff8800b8d1a800 ti: ffff880035860000 task.ti: ffff880035860000
[ 3342.491713] RIP: 0010:[<ffffffffc08ae035>]  [<ffffffffc08ae035>] dis_dev_get+0x15/0x40 [bbswitch]
[ 3342.491928] RSP: 0018:ffff880035863d10  EFLAGS: 00010202
[ 3342.492133] RAX: 6e6f697461727564 RBX: 0000000000000003 RCX: 0000000000000002
[ 3342.492335] RDX: 0000000000000000 RSI: 0000000000000003 RDI: ffffffffc08b0000
[ 3342.492535] RBP: ffff880035863d18 R08: ffffffff814e00e0 R09: 0000000000000000
[ 3342.492737] R10: 0000000000000000 R11: 0000000fffffffe0 R12: 0000000000000000
[ 3342.492939] R13: 00000000fffffffa R14: ffffffff81cd3f90 R15: 0000000000000000
[ 3342.493142] FS:  00007f8b8e80d740(0000) GS:ffff88013fd00000(0000) knlGS:0000000000000000
[ 3342.493345] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 3342.493529] CR2: 00007f8b8f73cf10 CR3: 000000009c68b000 CR4: 00000000000407e0
[ 3342.493529] Stack:
[ 3342.493529]  ffffffffc08ae545 ffff880035863d58 ffffffff81093f2d ffffffff81ec685c
[ 3342.493529]  ffffffff81c521c0 0000000000000003 0000000000000000 00000000ffffffff
[ 3342.493529]  0000000000000000 ffff880035863da8 ffffffff81094188 ffff880035863d48
[ 3342.493529] Call Trace:
[ 3342.493529]  [<ffffffffc08ae545>] ? bbswitch_pm_handler+0x55/0x70 [bbswitch]
[ 3342.493529]  [<ffffffff81093f2d>] notifier_call_chain+0x4d/0x70
[ 3342.493529]  [<ffffffff81094188>] __blocking_notifier_call_chain+0x58/0x80
[ 3342.493529]  [<ffffffff810941c6>] blocking_notifier_call_chain+0x16/0x20
[ 3342.493529]  [<ffffffff810bd5fa>] pm_notifier_call_chain+0x1a/0x30
[ 3342.493529]  [<ffffffff8178aafa>] suspend_prepare+0x46/0xcd
[ 3342.493529]  [<ffffffff810be83f>] enter_state+0x16f/0x250
[ 3342.493529]  [<ffffffff810be93b>] pm_suspend+0x1b/0x60
[ 3342.493529]  [<ffffffff810bd24e>] state_store+0x8e/0xf0
[ 3342.493529]  [<ffffffff8125ecab>] ? kernfs_fop_write+0x5b/0x170
[ 3342.493529]  [<ffffffff813973ff>] kobj_attr_store+0xf/0x30
[ 3342.493529]  [<ffffffff8125fc71>] sysfs_kf_write+0x41/0x50
[ 3342.493529]  [<ffffffff8125ed56>] kernfs_fop_write+0x106/0x170
[ 3342.493529]  [<ffffffff811e9e57>] vfs_write+0xc7/0x1f0
[ 3342.493529]  [<ffffffff811ea35f>] SyS_write+0x4f/0xb0
[ 3342.493529]  [<ffffffff817a46ed>] system_call_fastpath+0x1a/0x1f
[ 3342.493529] Code: d2 48 c7 c6 e0 e0 8a c0 48 89 e5 e8 b6 f2 95 c0 5d c3 0f 1f 40 00 66 66 66 66 90 48 8b 05 04 24 00 00 48 8b 40 10 48 85 c0 74 1f <48> 8b 78 38 48 85 ff 74 16 55 48 81 c7 98 00 00 00 be 04 00 00 
[ 3342.493529] RIP  [<ffffffffc08ae035>] dis_dev_get+0x15/0x40 [bbswitch]
[ 3342.493529]  RSP <ffff880035863d10>
[ 3342.498777] ---[ end trace 1c9a645295e2191f ]---


As additional info, my xorg.conf contains a section for backlight to work around Bug #1178796 :
Section "Device"
        Identifier      "Default Device"
        Option     "Backlight"  "intel_backlight"
        Driver      "intel"
        BusID       "PCI:0:2:0"
EndSection