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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - hdmi audio: spec violation for >=uhd-4k TMDS clock frequencies, no audio out in worst case"
href="https://bugs.freedesktop.org/show_bug.cgi?id=90776">90776</a>
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<th>Summary</th>
<td>hdmi audio: spec violation for >=uhd-4k TMDS clock frequencies, no audio out in worst case
</td>
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<th>Product</th>
<td>DRI
</td>
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<th>Version</th>
<td>DRI git
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<th>Hardware</th>
<td>x86-64 (AMD64)
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<th>OS</th>
<td>Linux (All)
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>critical
</td>
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>DRM/Intel
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<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>Reporter</th>
<td>joe.konno@linux.intel.com
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<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<pre>It is believed that Intel GPUs which support uhd-4k/3840x2160 resolutions over
HDMI are not setting N/CTS values correctly during audio(-over-hdmi) playback.
This can result in no audio being played back over the display's speakers.
The HDMI >=1.4 spec specifies audio sampling rate, TMDS clock frequencies, and
N/CTS values for uhd-4k displays. The N/CTS values are not being supported for
the TMDS clock frequencies associated with uhd-4k displays.
In the i915 display code there needs to be a mechanism for kernel audio drivers
(e.g. HDA) to signal the display driver when the audio sampling rate changes,
which will trigger a lookup within the display driver to ensure correct N/CTS
values are set.</pre>
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