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<base href="https://bugs.freedesktop.org/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [hsw DP] DP hot plug monitor discovery takes way too long"
href="https://bugs.freedesktop.org/show_bug.cgi?id=86733">86733</a>
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<th>Summary</th>
<td>[hsw DP] DP hot plug monitor discovery takes way too long
</td>
</tr>
<tr>
<th>Product</th>
<td>DRI
</td>
</tr>
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<th>Version</th>
<td>unspecified
</td>
</tr>
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<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
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<th>OS</th>
<td>Linux (All)
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
</td>
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<th>Component</th>
<td>DRM/Intel
</td>
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<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
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<th>Reporter</th>
<td>dimitri.j.ledkov@intel.com
</td>
</tr>
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<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=110049" name="attach_110049" title="dp-screen-finding-takes-too-long.txt">attachment 110049</a> <a href="attachment.cgi?id=110049&action=edit" title="dp-screen-finding-takes-too-long.txt">[details]</a></span>
dp-screen-finding-takes-too-long.txt
I'm attaching a log booted without any screens attached, with drm.debug=7 set
on the kernel command line, and later a screen attached.
[ 10.814093] [drm:intel_hpd_irq_handler] hotplug event received, stat
0x00400000, dig 0x10101210
[ 10.816202] [drm:drm_dp_i2c_do_msg] native defer
-- " --
[ 11.142132] [drm:drm_detect_monitor_audio] Monitor has basic audio support
...
[ 11.143836] [drm:drm_dp_i2c_do_msg] native defer
-- " --
[ 11.466765] [drm:drm_detect_monitor_audio] Monitor has basic audio support
[ 11.467203] [drm:drm_dp_i2c_do_msg] native defer
-- " --
[ 11.791475] [drm:drm_dp_i2c_do_msg] native defer
[ 11.792287] [drm:drm_add_display_info] DP-1: Assigning EDID-1.4 digital sink
color depth as 8 bpc.
Imho the amount of "[drm:drm_dp_i2c_do_msg] native defer" calls is a lot and
takes too much time.
For example, kernel initialisation takes 1.5s with screen attached (as reported
by systemd-analyse), however it takes ~750ms less if no screen is attached and
as per above the bulk of that time on screen hotplug is spent in talking over
i2c. Also not sure why, but "Monitor has basic audio support" is detected
twice...
This is an Intel NUC Haswell platform.</pre>
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