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<base href="https://bugs.freedesktop.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Sometimes does not detect 60Hz Full HD mode for external display, switching to 60 Hz with interlace"
href="https://bugs.freedesktop.org/show_bug.cgi?id=104934">104934</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Sometimes does not detect 60Hz Full HD mode for external display, switching to 60 Hz with interlace
</td>
</tr>
<tr>
<th>Product</th>
<td>DRI
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
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<th>OS</th>
<td>Linux (All)
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Component</th>
<td>DRM/Intel
</td>
</tr>
<tr>
<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>Martin@Lichtvoll.de
</td>
</tr>
<tr>
<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>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=137163" name="attach_137163" title="Xorg log with what I believe is todays output">attachment 137163</a> <a href="attachment.cgi?id=137163&action=edit" title="Xorg log with what I believe is todays output">[details]</a></span>
Xorg log with what I believe is todays output
On Linux 4.15.0-tp520-btrfstrim+ (4.15 + a small patch to fix BTRFS SSD
trimming, compiled with gcc 7.3.0 for full generic retpoline) on a ThinkPad
T520 with Intel Sandybridge graphics sometimes on rebooting or also after a
resume from hibernate to disk or suspend to RAM the external 24 inch Fujitsu
P24T-7 LED display connected via ThinkPad Minidock display port shows the
screen with visible flickering.
In this case xrandr shows:
DP-3 connected 1920x1080+1920+0 (normal left inverted right x axis y axis)
531mm x 299mm
1920x1080i 60.00* 50.00 59.94
1600x900 60.00
1280x1024 75.02 60.02
1440x900 59.89
1280x720 60.00 50.00 59.94
1024x768 75.03 60.00
800x600 75.00 60.32
720x576 50.00
720x480 60.00 59.94
640x480 75.00 60.00 59.94
720x400 70.08
When disconnecting the DisplayPort cable and reconnecting it or with
disconnecting the laptop from the dock and putting it back on it, Intel DRM/KMS
eventually recognizes again that the display and cable are capable of doing
1920x1080 with 60 Hz. After switching the resolution via Plasma´s
Systemsettings or directly via xrandr this looks like:
DP-3 connected 1920x1080+1920+0 (normal left inverted right x axis y axis)
531mm x 299mm
1920x1080 60.00 + 50.00 50.00 59.94
1920x1080i 60.00* 50.00 59.94
1680x1050 59.95
1600x900 60.00
1280x1024 75.02 60.02
1440x900 59.89
1280x720 60.00 50.00 59.94
1024x768 75.03 60.00
800x600 75.00 60.32
720x576 50.00
720x480 60.00 59.94
640x480 75.00 60.00 59.94
720x400 70.08
I am testing meanwhile with the third DisplayPort cable, which should be able
to even transfer UltraHD 4K resolutions.
Some kernel and X.org releases back this issue never happened. I did not report
it immediately as its again a "it happens sometimes" issue with no clear
pattern to reproduce it.
In the failure case I usually see nothing in dmesg. Today I saw:
[191597.165942] [drm:intel_set_pch_fifo_underrun_reporting [i915]] *ERROR*
uncleared pch fifo underrun on pch transcoder B
[191597.165952] [drm:cpt_irq_handler [i915]] *ERROR* PCH transcoder B FIFO
underrun
I don´t know whether this is related.
I attach a trimmed Xorg.0.log with what I believe is todays output.
Some hardware information:
% inxi -v1
System: Host: merkaba Kernel: 4.15.0-tp520-btrfstrim+ x86_64 bits: 64
Console: tty 6
Distro: Debian GNU/Linux buster/sid
CPU: Dual core Intel Core i5-2520M (-MT-MCP-) speed/max: 845/3200 MHz
Graphics: Card: Intel 2nd Generation Core Integrated Graphics Controller
Display Server: X.Org 1.19.6 driver: modesetting Resolution:
<a href="mailto:1920x1080@60.00hz">1920x1080@60.00hz</a>, <a href="mailto:1920x1080@60.00hz">1920x1080@60.00hz</a>
OpenGL: renderer: Mesa DRI Intel Sandybridge Mobile version: 3.3
Mesa 17.3.3
Drives: HDD Total Size: 780.2GB (58.8% used)
Info: Processes: 348 Uptime: 5 days Memory: 4809.4/15825.4MB Client: Shell
(zsh) inxi: 2.3.56
% phoronix-test-suite system-info
[…]
GRAPHICS: Intel Sandybridge Mobile 1536MB (1300MHz)
OpenGL: 3.3 Mesa 17.3.3
Display Driver: modesetting 1.19.6
Monitor: P24T-7 LED
Screen: 3840x1080
[…]</pre>
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