[Intel-gfx] Screen locksup with only black screen and cursor

[Chris]

I upgraded to the 3.19.0 kernel several days ago on my Ubuntu 14.04.2
LTS system running on a Dell Optiplex 780 with 4Gb ram kernel
3.19.0-031900-generic #201502091451 SMP Mon Feb 9 14:52:52 UTC 2015
x86_64 x86_64 x86_64 GNU/Linux. Since then quite often I'll see this in
my syslog:

Feb 22 18:00:46 localhost kernel: [ 9088.033815]
[drm:intel_crtc_cursor_set_obj] cursor off
Feb 22 18:00:46 localhost kernel: [ 9088.033821] [drm:g4x_check_srwm] SR
watermark: display plane 92, cursor 2
Feb 22 18:00:46 localhost kernel: [ 9088.033822] [drm:g4x_check_srwm]
display watermark is too large(92/63), disabling
Feb 22 18:00:46 localhost kernel: [ 9088.033824]
[drm:intel_set_memory_cxsr] memory self-refresh is disabled
Feb 22 18:00:46 localhost kernel: [ 9088.033826] [drm:g4x_update_wm]
Setting FIFO watermarks - A: plane=40, cursor=2, B: plane=2, cursor=2,
SR: plane=0, cursor=0

Quite often I'll also come to a black screen with only the mouse cursor.
The cursor will move however I can't get back to the desktop. Today when
this happened I was able to CTRL>ALT>ESC, login and run sudo reboot
which rebooted the system. I really don't know if any of the above has
anything to do with the lockups but if there are any other log items I
need to look for I'll gladly do it. I have hourly log snippets for
months. I'm also attaching the output of lshw and dmidecode in case it
helps.

http://pastebin.com/GDKCfGCX lshw

http://pastebin.com/KH9aknM2 dmidecode

I'm not sure even if this is the correct list to post to. If not
possibly someone could point me to the correct place to post and whether
or not to file a bug report and where to file it.

Thanks for your time

Chris

-- 
Chris
KeyID 0xE372A7DA98E6705C
31.11°N 97.89°W (Elev. 1092 ft)
07:49:44 up 44 min, 1 user, load average: 0.24, 0.25, 0.31
Ubuntu 14.04.2 LTS, kernel 3.19.0-031900-generic