[Bug 93826] 2560x1440 @144Hz graphic glitches and bad refresh rate

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=93826

--- Comment #67 from Alex Deucher <alexdeucher at gmail.com> ---
(In reply to iuno from comment #66)
> (In reply to Alex Deucher from comment #65)
> > 
> > Yes, that is independent of the patch in attachment 131983 [details] [review]
> > [review].  The driver disables dynamic mclk switching for refresh rates
> > above 120 hz to avoid flickering.
> 
> Yes, I know it prevents flickering. Comment #62 was a reply and I mentioned
> this as *another* problem (high power draw), independent from the fixed one.
> 

Do you get flickering at 144Hz without forcing the mclk to high?  I.e., without
these patches:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0a646f331db0eb9efc8d3a95a44872036d441d58
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=58d7e3e427db1bd68f33025519a9468140280a75
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=09be4a5219610a6fae3215d4f51f948d6f5d2609
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2275a3a2fe9914ba6d76c8ea490da3c08342bd19

> Do you know how this works on Windows? Do they increase voltage without
> raising clocks and could this be an option for amdgpu too?

It's not the mclk frequency or voltage, it's the blanking period for the
display timing, it's apparently too short on some monitors at very high refresh
rates for the mclk to finish switching in time.  If part of the mclk switch
happens outside of the vblank period, you end up with flickering or other
display artifacts.

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