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<body><span class="vcard"><a class="email" href="mailto:dhinakaran.pandiyan@intel.com" title="Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>"> <span class="fn">Dhinakaran Pandiyan</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Some DP MST hubs cause the driver to get stuck in link training clock recovery loop on hot-plugging"
href="https://bugs.freedesktop.org/show_bug.cgi?id=107281">bug 107281</a>
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<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Status</td>
<td>ASSIGNED
</td>
<td>RESOLVED
</td>
</tr>
<tr>
<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>FIXED
</td>
</tr></table>
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<div>
<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Some DP MST hubs cause the driver to get stuck in link training clock recovery loop on hot-plugging"
href="https://bugs.freedesktop.org/show_bug.cgi?id=107281#c2">Comment # 2</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Some DP MST hubs cause the driver to get stuck in link training clock recovery loop on hot-plugging"
href="https://bugs.freedesktop.org/show_bug.cgi?id=107281">bug 107281</a>
from <span class="vcard"><a class="email" href="mailto:dhinakaran.pandiyan@intel.com" title="Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>"> <span class="fn">Dhinakaran Pandiyan</span></a>
</span></b>
<pre>commit 65172699a8bd9956705f71fb8b66b1068a1bb5cd
Author: Dhinakaran Pandiyan <<a href="mailto:dhinakaran.pandiyan@intel.com">dhinakaran.pandiyan@intel.com</a>>
Date: Wed Jul 18 10:19:43 2018 -0700
drm/i915/mst: Continue state updates even if AUX writes fail.
We are too late in the enabling sequence to back out cleanly, not updating
state tracking variables, like intel_dp->active_mst_links in this
instance, results in incorrect behaviour further along.
v2: Fixed int v/s bool comparison
Cc: Ville Syrjälä <<a href="mailto:ville.syrjala@linux.intel.com">ville.syrjala@linux.intel.com</a>>
Cc: Rodrigo Vivi <<a href="mailto:rodrigo.vivi@intel.com">rodrigo.vivi@intel.com</a>>
Cc: Nathan Ciobanu <<a href="mailto:nathan.d.ciobanu@linux.intel.com">nathan.d.ciobanu@linux.intel.com</a>>
Bugzilla: <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Some DP MST hubs cause the driver to get stuck in link training clock recovery loop on hot-plugging"
href="show_bug.cgi?id=107281">https://bugs.freedesktop.org/show_bug.cgi?id=107281</a>
Signed-off-by: Dhinakaran Pandiyan <<a href="mailto:dhinakaran.pandiyan@intel.com">dhinakaran.pandiyan@intel.com</a>>
Reviewed-by: Nathan Ciobanu <<a href="mailto:nathan.d.ciobanu@linux.intel.com">nathan.d.ciobanu@linux.intel.com</a>>
Tested-by: Nathan Ciobanu <<a href="mailto:nathan.d.ciobanu@linux.intel.com">nathan.d.ciobanu@linux.intel.com</a>>
Reviewed-by: Rodrigo Vivi <<a href="mailto:rodrigo.vivi@intel.com">rodrigo.vivi@intel.com</a>>
Link:
<a href="https://patchwork.freedesktop.org/patch/msgid/20180718171943.3246-2-dhinakaran.pandiyan@intel.com">https://patchwork.freedesktop.org/patch/msgid/20180718171943.3246-2-dhinakaran.pandiyan@intel.com</a>
commit 45ef40aab72e21eb81147a6e8a2bca863f0234fd
Author: Dhinakaran Pandiyan <<a href="mailto:dhinakaran.pandiyan@intel.com">dhinakaran.pandiyan@intel.com</a>>
Date: Wed Jul 18 10:19:42 2018 -0700
drm/i915/mst: Do not retrain new links
The short pulse handler checks if channel equalization is okay and
goes onto retrain a link if there are active MST links. This retraining
path is not meant for new MST connections, but due to a bug elsewhere, if
active_mst_links is < 0 the boolean check for active_mst_links passes and
we proceed to retrain a new link. This results in a sequence of failed link
training attempts, most likely due to the hardware not setup for link
training at that point i.e., missing the DDI pre_enable sequence.
[ 80.301272] [drm:intel_dp_check_mst_status] channel EQ not ok,
retraining
[ 80.301312] [drm:intel_ddi_prepare_link_retrain] *ERROR* Timeout waiting
for DDI BUF C idle bit
The above error gives us a hint something went wrong before link
training started.
Check for a positive value of active_mst_links and throw in a warning for
invalid active_mst_links as debug aid.
Cc: Nathan Ciobanu <<a href="mailto:nathan.d.ciobanu@linux.intel.com">nathan.d.ciobanu@linux.intel.com</a>>
Cc: Rodrigo Vivi <<a href="mailto:rodrigo.vivi@intel.com">rodrigo.vivi@intel.com</a>>
Signed-off-by: Dhinakaran Pandiyan <<a href="mailto:dhinakaran.pandiyan@intel.com">dhinakaran.pandiyan@intel.com</a>>
Tested-by: Nathan Ciobanu <<a href="mailto:nathan.d.ciobanu@linux.intel.com">nathan.d.ciobanu@linux.intel.com</a>>
Reviewed-by: Rodrigo Vivi <<a href="mailto:rodrigo.vivi@intel.com">rodrigo.vivi@intel.com</a>>
Link:
<a href="https://patchwork.freedesktop.org/patch/msgid/20180718171943.3246-1-dhinakaran.pandiyan@intel.com">https://patchwork.freedesktop.org/patch/msgid/20180718171943.3246-1-dhinakaran.pandiyan@intel.com</a></pre>
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