On a zotac ci320 nano with ubuntu trusty server 14.04.3 LTS and kernel 
from openelec forum 3.19.1-legacy-turbo+ with yavdr
unstable installed and va-api-glx in softhddevice vdr plugin a kernel oops
left the following trace, maybe usefull because freezes normally don't leave
a trace in the logs,..

Nov 17 22:12:55 nano4 kernel: [ 4740.991238] ------------[ cut here ]------------
Nov 17 22:12:55 nano4 kernel: [ 4740.991365] WARNING: CPU: 3 PID: 134 at drivers/gpu/drm/i915/intel_pm.c:4492 valleyview_set_rps+0x167/0x1a0 [i915]()
Nov 17 22:12:55 nano4 kernel: [ 4740.991375] WARN_ON(val > dev_priv->rps.max_freq_softlimit)
Nov 17 22:12:55 nano4 kernel: [ 4740.991383] Modules linked in: msr(E) autofs4(E) rc_tt_1500(OE) ts2020(OE) m88ds3103(OE) i2c_mux(E) arc4(E) intel_rapl(E) intel_powerclamp(E) snd_hda_codec_hdmi(E) snd_hda_codec_realtek(E) snd_hda_codec_generic(E) kvm(E) crct10dif_pclmul(E) crc32_pclmul(E) dvb_usb_dw2102(OE) dvb_usb(OE) ghash_clmulni_intel(E) iwlmvm(E) cryptd(E) dvb_core(OE) snd_soc_rt5640(E) mac80211(E) media(OE) snd_hda_intel(E) snd_soc_rl6231(E) snd_hda_controller(E) snd_intel_sst_acpi(E) snd_intel_sst_core(E) snd_soc_sst_mfld_platform(E) snd_hda_codec(E) snd_soc_core(E) serio_raw(E) snd_compress(E) iwlwifi(E) btusb(E) snd_pcm_dmaengine(E) snd_hwdep(E) cfg80211(E) snd_pcm(E) snd_seq_midi(E) snd_seq_midi_event(E) ir_lirc_codec(OE) ir_xmp_decoder(OE) lirc_dev(OE) ir_mce_kbd_decoder(OE) mei_txe(E) iosf_mbi(E) ir_sharp_decoder(OE) mei(E) lpc_ich(E) shpchp(E) ir_sanyo_decoder(OE) snd_rawmidi(E) ir_sony_decoder(OE) ir_jvc_decoder(OE) ir_rc6_decoder(OE) ir_rc5_decoder(OE) snd_seq(E) ir_nec_decoder(OE) snd_seq_device(E) snd_timer(E) rc_rc6_mce(OE) nuvoton_cir(OE) rc_core(OE) 8250_fintek(E) snd(E) rfcomm(E) bnep(E) dw_dmac(E) dw_dmac_core(E) i2c_hid(E) hid(E) rfkill_gpio(E) soundcore(E) bluetooth(E) snd_soc_sst_acpi(E) 8250_dw(E) spi_pxa2xx_platform(E) i2c_designware_platform(E) i2c_designware_core(E) pwm_lpss_platform(E) mac_hid(E) pwm_lpss(E) i915(E) video(E) drm_kms_helper(E) nfsd(E) drm(E) auth_rpcgss(E) nfs_acl(E) i2c_algo_bit(E) nfs(E) lockd(E) grace(E) sunrpc(E) fscache(E) nct6775(E) hwmon_vid(E) coretemp(E) lp(E) parport(E) nls_iso8859_1(E) psmouse(E) r8169(E) mii(E) ahci(E) libahci(E) sdhci_acpi(E) sdhci(E)
Nov 17 22:12:55 nano4 kernel: [ 4740.991767] CPU: 3 PID: 134 Comm: kworker/3:2 Tainted: G           OE  3.19.1-legacy-turbo+ #1
Nov 17 22:12:55 nano4 kernel: [ 4740.991778] Hardware name: Motherboard by ZOTAC ZBOX-CI320NANO series/ZBOX-CI320NANO series, BIOS B219P026 05/19/2015
Nov 17 22:12:55 nano4 kernel: [ 4740.991859] Workqueue: events intel_gen6_powersave_work [i915]
Nov 17 22:12:55 nano4 kernel: [ 4740.991871]  ffffffffc06cb3c8 ffff88003655fcc8 ffffffff8179acb0 0000000000000000
Nov 17 22:12:55 nano4 kernel: [ 4740.991890]  ffff88003655fd18 ffff88003655fd08 ffffffff81073a7a ffff88003655fcf8
Nov 17 22:12:55 nano4 kernel: [ 4740.991908]  ffff880078550000 00000000000000d6 00000000000000d6 ffff880077acd000
Nov 17 22:12:55 nano4 kernel: [ 4740.991927] Call Trace:
Nov 17 22:12:55 nano4 kernel: [ 4740.991968]  [<ffffffff8179acb0>] dump_stack+0x45/0x57
Nov 17 22:12:55 nano4 kernel: [ 4740.991993]  [<ffffffff81073a7a>] warn_slowpath_common+0x8a/0xc0
Nov 17 22:12:55 nano4 kernel: [ 4740.992013]  [<ffffffff81073af6>] warn_slowpath_fmt+0x46/0x50
Nov 17 22:12:55 nano4 kernel: [ 4740.992111]  [<ffffffffc0620467>] valleyview_set_rps+0x167/0x1a0 [i915]
Nov 17 22:12:55 nano4 kernel: [ 4740.992202]  [<ffffffffc0621ecf>] intel_gen6_powersave_work+0xb2f/0x11b0 [i915]
Nov 17 22:12:55 nano4 kernel: [ 4740.992223]  [<ffffffff8108c6cf>] process_one_work+0x14f/0x400
Nov 17 22:12:55 nano4 kernel: [ 4740.992241]  [<ffffffff8108ce68>] worker_thread+0x118/0x510
Nov 17 22:12:55 nano4 kernel: [ 4740.992259]  [<ffffffff8108cd50>] ? rescuer_thread+0x3d0/0x3d0
Nov 17 22:12:55 nano4 kernel: [ 4740.992278]  [<ffffffff81092252>] kthread+0xd2/0xf0
Nov 17 22:12:55 nano4 kernel: [ 4740.992298]  [<ffffffff81092180>] ? kthread_create_on_node+0x180/0x180
Nov 17 22:12:55 nano4 kernel: [ 4740.992319]  [<ffffffff817a26fc>] ret_from_fork+0x7c/0xb0
Nov 17 22:12:55 nano4 kernel: [ 4740.992339]  [<ffffffff81092180>] ? kthread_create_on_node+0x180/0x180
Nov 17 22:12:55 nano4 kernel: [ 4740.992352] ---[ end trace 6a13023d6ab83790 ]---