Refresh rate/backlight flicker using drivers >358 in Ubuntu 16.x

I’ve got a GTX-580 powering a newer 1920x1080 display and a fairly old LG at 1280x1024.

Using any driver lower than 358 both displays work fine. All the drivers after 358 cause the LG display to exhibit refresh rate flickering at its native resolution and refresh rate (60.02Hz). Any resolutions lower than this work as they should.

I’ve tried using both HDMI and DVI with the same result. EDID is being read fine, the monitor shows up as it should in the Nvidia settings.

Any suggestions?

1 Like

I’ve now run the debug script on every driver from 340 up and done diff comparisons on the results and there are no significant differences between them, and no noticeable errors; certainly nothing that would explain my problem.

I managed to override my monitor’s EDID enough to set the rate to 59Hz and 65Hz with no noticeable difference.

This is infuriating, especially given the improvements to offloading in 375 are fairly substantial. As things are I’m getting better performance from the beta Xorg drivers - the slight cursor flicker on window transition is much less impactful than the eyestrain-o-rama I’ve got going on with the recent releases.

Having tried multiple mode settings with no success I finally found out flat panels don’t suffer refresh rate problems (I’m old, I’ve spent too long with CRTs), so this is most likely a backlighting issue.

Reading around it appears there are potential issues with both Panel Self Refresh and Frame Buffer Compression, but those should apparently only be a problem with kernels above 4.5-ish. It also looks lke they might be exclusive to the i915 driver.

Is there anywhere I can properly submit the pertinent bug report logs I’ve got? All the links I’ve managed to find on the site are dead.

I decided to take one final Hail Mary at this as the few remaining quirks of the Xorg drivers were getting a little frustrating.

After weeks of hair-tearing frustration the fix was trivially, trivially easy - I changed the ‘Brightness’ level in the relevant monitor’s ‘Color Correction’ tab in the Nvidia settings, then I changed it back. It was that damned simple.

It doesn’t, however, work flawlessly. The problem always appears on a restart. Additionally, the slider/value will often need to be changed multiple times before you ‘luck out’ and the flickering stops (I’m glad it worked without issue the very first time I tried it, or I’d have given it up as a lost cause).

EDIT: Right, I have a guaranteed fix! Changing the ‘Dithering Mode’ in the ‘Controls’ tab to ‘Static’ completely eliminates the issue!

Now that I’ve confirmed it is 100% a software issue (not that I had any doubt) may I ask, again, where to properly submit bug reports? There’s quite obviously no point submitting them in this forum.

1 Like

Wow, it actually worked. I was trying to fix this issue with no luck for the past days. Thanks a lot.