Description of problem:
Until kernel version 4.15.17-300 the i915.enable_rc6=0 in the boot was respected and my screen did not flicker.
Version-Release number of selected component (if applicable):
4.16.3-200 and 4.16.5-200
If I boot on the newer kernels my screen flickers
Steps to Reproduce:
1. Reboot do not select the old kernel
Laptop Yoga 910
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fb6db0f5bf1d4d3a4af6242e287fa795221ec5b8 so it looks like it was removed intentionally . This is best tracked as a bug at bugzilla.freedesktop.org
*** Bug 1573112 has been marked as a duplicate of this bug. ***
I'm not familiar with freedesktop.org.
I cannot find a kernel product to file the bug under.
I'm also affected by this issue.
In my case, disabling some CPU c-states as suggested in https://bugs.freedesktop.org/show_bug.cgi?id=105962 seems to do the trick.
Using intel_idle.max_cstate=1 prevents the flickering, as well as allowing c-states up to 5. With max_cstate=6 the flickering is back.
I have a Late 2017 Razer Blade Stealth w/ 8550 CPU. As of the 4.16 kernel, I too saw the flickering return.
For me, setting the max_cstate for the processor stopped the flickering as well. In my case, however, anything above 4 would cause the flickering to return.
I've tried to use the intel_idle.max_cstate=1 with no good result, unfortunately.
Sorry for the ticket hijacking then; this solution may be razer blade stealth specific (having an i7 7500U late 2016 RBS here).
(In reply to klaus from comment #6)
> I've tried to use the intel_idle.max_cstate=1 with no good result,
My bad. I may have mistyped the setting when using a Danish keyboard - not familiar with a USAnian keyboard.
I've just tried once again and now recent kernels boots without flickering on the screen.
So to conclude the intel_idle.max_cstate=1 is a fine workaround for me.
(In reply to klaus from comment #8)
> (In reply to klaus from comment #6)
> > I've tried to use the intel_idle.max_cstate=1 with no good result,
> > unfortunately.
> My bad. I may have mistyped the setting when using a Danish keyboard - not
> familiar with a USAnian keyboard.
> I've just tried once again and now recent kernels boots without flickering
> on the screen.
> So to conclude the intel_idle.max_cstate=1 is a fine workaround for me.
As far as I understand it seems that this workaround is a more fine grained one than i915.enable_rc6=0. You might want to try to allow higher c-states too, to allow more power saving modes.
One have to understand what is the effect of this particular setting, which I do not. Does it influence on the power usage?
(In reply to klaus from comment #10)
> One have to understand what is the effect of this particular setting, which
> I do not. Does it influence on the power usage?
If I understand correctly (it would be nice to have a better explanation), rc6 is an intel GPU deep power saving mode. By disabling it, a side effect is to disable the whole CPU power saving modes (c-states). The various c-states are more or less deep power saving modes, that puts to sleep various units of the CPU.
More infos here https://software.intel.com/en-us/articles/power-management-states-p-states-c-states-and-package-c-states or here https://gist.github.com/wmealing/2dd2b543c4d3cff6cab7
I'm actually experiencing hard lockups when using my laptop on battery again. I used to have these with the older kernel, but setting i915.enable_rc6=0 was fixing it.
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