i915 stop working after linux 4.2.0-21-generic

[B.]

Hello,

After updating the linux kernel of my Ubuntu 15.10 from 4.2.0-21 to 4.2.0.22
I was unable to get to XFCE and slim login manager, I was stuck on a black screen
with nothing displayed (no text/graphics). Same issue with latest 4.2.0.25.
When I go back to 4.2.0-21 everything is working perfectly.

So something is "broken" with i915 module starting 4.2.0.22 and newer.

After some research online, I managed to make it work even with kernel 4.2.25
by doing this vodoo magic magic. It's not clear what made it work ;-P

# /etc/default/grub
GRUB_CMDLINE_LINUX="libata.force=noncq quirks.mbp_force_ahci=1 acpi_backlight=vendor apple_bl.use_gmux=1 reboot=pci i915.enable_ips=0 i915.i915_enable_fbc=1 i915.i915_enable_rc6=1 i915.lvds_channel_mode=2 i915.modeset=1 i915.lvds_use_ssc=0 intel_pstate=disable"

# /etc/modprobe.d/i915.conf
options i915 semaphores=1

# /etc/modprobe.d/blacklist
blacklist intel_pstate

reboot

lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 15.10
Release: 15.10
Codename: wily

uname -a
Linux **** 4.2.0-25-generic #30-Ubuntu SMP Mon Jan 18 12:31:50 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

dmidecode -s system-product-name
Macmini7,1

lspci -vv
00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller])
        Subsystem: Apple Inc. Device 0141
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0
        Interrupt: pin A routed to IRQ 56
        Region 0: Memory at a0000000 (64-bit, non-prefetchable) [size=4M]
        Region 2: Memory at 90000000 (64-bit, prefetchable) [size=256M]
        Region 4: I/O ports at 2000 [size=64]
        Expansion ROM at <unassigned> [disabled]
        Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
                Address: fee00018 Data: 0000
        Capabilities: [d0] Power Management version 2
                Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [a4] PCI Advanced Features
                AFCap: TP+ FLR+
                AFCtrl: FLR-
                AFStatus: TP-
        Kernel driver in use: i915

[Brad Figg (brad-figg)]

This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:

apport-collect 1536567

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Joseph Salisbury (jsalisbury)]

I started a kernel bisect between Ubuntu-4.2.0-21.25 and Ubuntu-4.2.0-22.27 . The kernel bisect will require testing of about 7-10 test kernels.

I built the first test kernel, up to the following commit:
efe9c433bb69890e7b925d845ce9443023bc882e

The test kernel can be downloaded from:
http://kernel.ubuntu.com/~jsalisbury/lp1536567

Can you test that kernel and report back if it has the bug or not? I will build the next test kernel based on your test results.

Thanks in advance

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu Wily) because there has been no activity for 60 days.]

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]