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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - [BSW] testdisplay shows black screen for HDMI 4K monitor"
href="https://bugs.freedesktop.org/show_bug.cgi?id=89002#c2">Comment # 2</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - [BSW] testdisplay shows black screen for HDMI 4K monitor"
href="https://bugs.freedesktop.org/show_bug.cgi?id=89002">bug 89002</a>
from <span class="vcard"><a class="email" href="mailto:ville.syrjala@linux.intel.com" title="Ville Syrjala <ville.syrjala@linux.intel.com>"> <span class="fn">Ville Syrjala</span></a>
</span></b>
<pre>(In reply to Jani Nikula from <a href="show_bug.cgi?id=89002#c1">comment #1</a>)
<span class="quote">> [ 4.836820] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU
> pipe C FIFO underrun
>
> Ville, can we do 4k on bsw hdmi?</span >
Not before we get the cdclk code fixed. These systems boot with cdclk @ 266MHz
which is too low. We need to increase it to 320MHz when driving 4k modes.
Patches are in some kind of review limbo, and there's another patch (reduce
cdclk guardband to 5% from 10%) I've not yet posted that is also needed for
HDMI 4k.</pre>
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