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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - [SKL][Audio][HD-A Display]: Can't detect Display audio codec if not connect HDMI and DP monitor when boot up"
href="https://bugs.freedesktop.org/show_bug.cgi?id=89419#c24">Comment # 24</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - [SKL][Audio][HD-A Display]: Can't detect Display audio codec if not connect HDMI and DP monitor when boot up"
href="https://bugs.freedesktop.org/show_bug.cgi?id=89419">bug 89419</a>
from <span class="vcard"><a class="email" href="mailto:jani.nikula@intel.com" title="Jani Nikula <jani.nikula@intel.com>"> <span class="fn">Jani Nikula</span></a>
</span></b>
<pre>(In reply to Libin Yang from <a href="show_bug.cgi?id=89419#c23">comment #23</a>)
<span class="quote">> As the hdmi audio can be deteced successfully when monitor is connected,
> could you please check what's the difference gfx driver will do freom
> monitor isn't connected?</span >
For one, you can't expect to be able to read the registers (or the read values
to make sense) *unless* you've called the ->get_power() function through the
component API. There are plenty of audio registers that i915 never touches but
need the power well from i915 to operate. And you should expect the registers
to lose their values after you ->put_power(). Check bspec.</pre>
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