[Intel-gfx] [regression] boot to the blackscreen with the kernel 4.3

[zhuhuachun]

hi,
     when use the latest 4.3-rc3kernel,
the fedora rawhide will boot to the blackscreen,and never got the gdm 
login screen.

the fellowing is the boot log about drm.
[drm] Initialized drm 1.1.0 20060810
[drm] Memory usable by graphics device = 2048M
[drm] Replacing VGA console driver
[drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[drm] Driver supports precise vblank timestamp query.
[drm:drm_calc_timestamping_constants [drm]] *ERROR* crtc 21: Can't 
calculate constants, dotclock = 0!
[drm] Initialized i915 1.6.0 20150731 for 0000:00:02.0 on minor 0


lspci
00:00.0 Host bridge: Intel Corporation 4 Series Chipset DRAM Controller 
(rev 03)
00:02.0 VGA compatible controller: Intel Corporation 4 Series Chipset 
Integrated Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation 4 Series Chipset 
Integrated Graphics Controller (rev 03)
00:03.0 Communication controller: Intel Corporation 4 Series Chipset 
HECI Controller (rev 03)
00:03.2 IDE interface: Intel Corporation 4 Series Chipset PT IDER 
Controller (rev 03)
00:03.3 Serial controller: Intel Corporation 4 Series Chipset Serial KT 
Controller (rev 03)
00:19.0 Ethernet controller: Intel Corporation 82567LM-3 Gigabit Network 
Connection (rev 02)
00:1a.0 USB controller: Intel Corporation 82801JD/DO (ICH10 Family) USB 
UHCI Controller #4 (rev 02)
00:1a.1 USB controller: Intel Corporation 82801JD/DO (ICH10 Family) USB 
UHCI Controller #5 (rev 02)
00:1a.2 USB controller: Intel Corporation 82801JD/DO (ICH10 Family) USB 
UHCI Controller #6 (rev 02)
00:1a.7 USB controller: Intel Corporation 82801JD/DO (ICH10 Family) USB2 
EHCI Controller #2 (rev 02)
00:1b.0 Audio device: Intel Corporation 82801JD/DO (ICH10 Family) HD 
Audio Controller (rev 02)
00:1d.0 USB controller: Intel Corporation 82801JD/DO (ICH10 Family) USB 
UHCI Controller #1 (rev 02)
00:1d.1 USB controller: Intel Corporation 82801JD/DO (ICH10 Family) USB 
UHCI Controller #2 (rev 02)
00:1d.2 USB controller: Intel Corporation 82801JD/DO (ICH10 Family) USB 
UHCI Controller #3 (rev 02)
00:1d.7 USB controller: Intel Corporation 82801JD/DO (ICH10 Family) USB2 
EHCI Controller #1 (rev 02)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev a2)
00:1f.0 ISA bridge: Intel Corporation 82801JDO (ICH10DO) LPC Interface 
Controller (rev 02)
00:1f.2 IDE interface: Intel Corporation 82801JD/DO (ICH10 Family) 
4-port SATA IDE Controller (rev 02)
00:1f.3 SMBus: Intel Corporation 82801JD/DO (ICH10 Family) SMBus 
Controller (rev 02)
00:1f.5 IDE interface: Intel Corporation 82801JD/DO (ICH10 Family) 
2-port SATA IDE Controller (rev 02)

thanks
chunshan