[Intel-gfx] Odd behavior change in HD 4600/i915 graphics with Fedora 20

[Paul Livingston]

I recently built a new desktop machine using a Shuttle SZ87R6, an I7-4770S and a Dell U2713HM monitor.  Did my initial HW burn-in and testing using a Fedora 20 KDE Spin Live CD (Kernel 3.11.10-301.fc20.x86_64 & KDE Systems settings v4.11.3) using the DVI port on the computer and display and a dual link DVD-D cable, everything worked fine and the display resolution was 2560x1440 (native for the display).  Both the monitor OSD and the KDE Systems Setting applet correctly reported both the resolution and the port DVI.  The last of the parts came in (HD for secondary storage) and I finished the build and did an ion disk nstall and a full system update (Kernel 3.14.8-200.fc20.x86_64 and KDE System Settings v4.11.10, along with ~=750MB of other updates)  The display looked odd after rebooting and when I checked it was set to 1600x1200 (not only wrong resolution but wrong aspect ratio) and the KDE applet now reported that the interface was HDMI vice the actual DVI.

Checked the U2713HM OSD and found that while the max resolution was 2560x1440, current resolution was 1600x1200 and the interface was correctly reported (DVI-D).  Verified the interconnection was DVI-D to DVI-D via a dual link DVI cable.  Went back inside the OS and rechecked the Display and Monitor settings in Systems Settings and maximum available resolution was 1600x1200 (which is what the display was set to). also noted that the Display and Monitor applet was reporting an HDMI interconnect vice the actual DVI-D.  Ran xrandr from the command line and found that while 1920x1200 was shown as an available resolution (at least the correct aspect ratio), I could not set it to that using the command line.   Scratched my head and spent several hours Googling to see if anyone else had run into this problem - no luck, although there were some postings from roughly a year ago about people in the Win8 world having video problems with the HD 4600 IGA.  I then spent some time on the Intel site, found several conflicting threads on HD 4600 capability and did an explicit update to the latest version of the Intel video stack for Linux.  No change and still unable to reset video resolution or aspect ratio from within F20.  BTW, going back to the earlier kernel is not really a viable option as I wanted the privilege  escalation bug fix that came out in 3.14.6, however with the earlier kernel both the resolution and aspect ratio is correct.

At this stage, I have pretty well established (at least in my own mind) that it is a SW vice a HW problem and it is entirely reproducible as when I reboot with the Live CD the 2560x1440 resolution comes up by default.  While at this point I rather strongly suspect the Intel i915 driver and video stack, it could also be either a KDE or an xorg or a kernel issue and I really don' know where to file a bug report since I can't nail down which SW is screwing up or what to try next.  Seems odd that Intel would disable a HW capability that was working just fine as part of a driver update, not sure what the rationale for that would be

Any ideas, insight or suggestions would be most welcome.  

Thanks

Paul Livingston
<pml at accokeekwoods.com>