This was initially discussed in bug #100440, which tracked a different issue. Attempting to enable the 2560x1440 mode with 12 bpc in an Acer S277HK monitor leads to a blank screen. from bug 100440, comment 19 > I also tested enabling the given mode with only scrambling and only high > tmds. > > scrambling high tmds result > yes yes fail > yes no pass > no yes fail > no no pass > > So this seems to be a combination of 12 bpc, a port clock in the range > [340,405) and high tmds ratios. But as far as I can tell, we are following > the spec with respect to those. Shashank, any ideas? from bug 100440, commend 32 > I was able to get this issue tested with a HDMI analyzer too. > Here are the updates: ... > - The display never fails when using the analyzer. It only fails using real > monitor. > - Scrambling and clock high ratio is getting enabled/set/disabled properly. > - Bootup and modeset dmesg logs attached. > > I think this is a fault with monitor, which is not able to handle this mode > at 12BPC (Also, This mode is a non-CEA modes, so not a standard one too)
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