[Bug 95392] Trying to set mode 3840x2160 at 60 Hz results in a crash

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=95392

--- Comment #9 from Oli <b52 at reaktor42.de> ---
(In reply to Ville Syrjala from comment #8)
> (In reply to Oli from comment #7)
> > (In reply to Ville Syrjala from comment #3)
> > > [   12.914535] [drm:intel_update_cdclk] Current CD clock rate: 450000 kHz
> > > [   91.861529] [drm:intel_dump_crtc_timings] crtc timings: 533280 3840 3848
> > > 3992 4000 2160 2214 2219 2222, type: 0x0 flags: 0x9
> > > 
> > > Your cdclk is too low for that mode. I have a branch which has the required
> > > bits to adjust cdclk dynamically on SKL:
> > > git://github.com/vsyrjala/linux.git skl_bxt_cdclk_part_2
> > > 
> > > Can you test with that branch?
> > 
> > I did and it seems to works, at least the display didn't blank and xrandr
> > reports 60 Hz. Though, I have no way to tell if this is really the case,
> > because my display won't show this information.
> > 
> > See the attached dmesg output for more information. I used the same
> > drm.debug settings as before.
> 
> 
> [    9.195675] [drm:intel_update_cdclk] Current CD clock rate: 450000 kHz,
> VCO: 8100000 kHz, ref: 24000 kHz
> [    9.195677] [drm:intel_update_max_cdclk] Max CD clock rate: 675000 kHz
> [    9.195678] [drm:intel_update_max_cdclk] Max dotclock rate: 675000 kHz
> [   70.790172] [drm:intel_dump_crtc_timings] crtc timings: 533280 3840 3848
> 3992 4000 2160 2214 2219 2222, type: 0x0 flags: 0x9
> [   70.790188] [drm:intel_modeset_checks] New cdclk calculated to be atomic
> 540000, actual 540000
> [   71.866294] [drm:skl_set_cdclk] Changing CDCLK to 540000 kHz (VCO 8100000
> kHz)
> [   71.872408] [drm:intel_update_cdclk] Current CD clock rate: 540000 kHz,
> VCO: 8100000 kHz, ref: 24000 kHz
> 
> So everything is looking good.
> 
> > 
> > PS: Is this fix going upstream some time?
> 
> It's being reviewed now, so should land soonish, I hope.

This has not really something to do with the bug, but how are these numbers to
interpret? I mean, shouldn't there be something like a '60' somewhere?

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