[Bug 91434] [IVB/HSW] 23.976Hz & 24Hz modes broken on dual-display with recent (4.0.x) kernels

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=91434

Ville Syrjala <ville.syrjala at linux.intel.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEEDINFO

--- Comment #33 from Ville Syrjala <ville.syrjala at linux.intel.com> ---
(In reply to Martin Andersen from comment #32)
> Tested with the latest kernel from drm-tip, 4.12.0-994_4.12.0-994. 50 & 60Hz
> modes only work intermittently, and with an erratic picture and white dots
> showing.
> 
> Reverting to either the 24.000Hz or 23.976Hz modes produces a stable picture.

Jun 18 15:11:33 meraxes kernel: [  179.206299] [drm:intel_hdmi_set_edid [i915]]
DP dual mode adaptor (type 2 HDMI) detected (max TMDS clock: 300000 kHz)
Jun 18 15:11:33 meraxes kernel: [  179.206401] [drm:drm_add_edid_modes.part.24
[drm]] HDMI: DVI dual 0, max TMDS clock 225000 kHz
Jun 18 15:11:33 meraxes kernel: [  179.219332] [drm:intel_dump_pipe_config
[i915]] crtc timings: 148500 1920 2008 2052 2200 1080 1084 1089 1125, type: 0x0
flags: 0x5
Jun 18 15:11:33 meraxes kernel: [  179.219362] [drm:intel_dump_pipe_config
[i915]] port clock: 222750, pipe src size: 1920x1080, pixel rate 148500

So both the projector and the DP->HDMI dongle are telling is that we can do
12bpc for 1080p @ 60hz, but the unstable picture is telling us something
different. I suspect the problem is with the dongle, the cable, or the
projector. Do you have other cables/dongles you can try?

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