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<body><span class="vcard"><a class="email" href="mailto:lorenz@math.tu-berlin.de" title="Benjamin Lorenz <lorenz@math.tu-berlin.de>"> <span class="fn">Benjamin Lorenz</span></a>
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<a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - [i915] intel_backlight does not function - Lenovo X1 Yoga OLED"
href="https://bugs.freedesktop.org/show_bug.cgi?id=97883">bug 97883</a>
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<td>lorenz@math.tu-berlin.de
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<b><a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - [i915] intel_backlight does not function - Lenovo X1 Yoga OLED"
href="https://bugs.freedesktop.org/show_bug.cgi?id=97883#c30">Comment # 30</a>
on <a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - [i915] intel_backlight does not function - Lenovo X1 Yoga OLED"
href="https://bugs.freedesktop.org/show_bug.cgi?id=97883">bug 97883</a>
from <span class="vcard"><a class="email" href="mailto:lorenz@math.tu-berlin.de" title="Benjamin Lorenz <lorenz@math.tu-berlin.de>"> <span class="fn">Benjamin Lorenz</span></a>
</span></b>
<pre>Created <span class=""><a href="attachment.cgi?id=137494" name="attach_137494" title="/dev/drm_dp_aux0 from X1 Yoga 2nd gen OLED">attachment 137494</a> <a href="attachment.cgi?id=137494&action=edit" title="/dev/drm_dp_aux0 from X1 Yoga 2nd gen OLED">[details]</a></span>
/dev/drm_dp_aux0 from X1 Yoga 2nd gen OLED
(In reply to Jani Nikula from <a href="show_bug.cgi?id=97883#c28">comment #28</a>)
<span class="quote">> If anyone can enable CONFIG_DRM_DP_AUX_CHARDEV=y and dump the DPCD using the
> aux chardev (IIRC should pop up somewhere under /sys/class/drm/card0-eDP-1),
> it might give some clues.</span >
Almost full DPCD data from X1 Yoga 2nd generation is attached.
Reading it with cat gives only the first few bytes and several
[drm:intel_dp_aux_ch] *ERROR* dp_aux_ch receive error status 0x6f4003ff
in dmesg.
ddrescue was able to extract everything except for byte 0x53:
# pos size status
0x00000000 0x00000053 +
0x00000053 0x00000001 -
0x00000054 0x000FFFAC +
The file is zeros except for the following parts:
00000000: 120a 8441 0000 0180 0200 0000 0f0b 0000 ...A............
00000060: 0111 0100 0100 0100 0001 0600 0000 0000 ................
00000070: 010b 0000 0000 0000 0000 0000 0000 0000 ................
00000100: 0a84 0000 0000 0000 0108 0000 0000 0000 ................
00000200: 0100 7777 0101 0000 0000 0000 0000 0000 ..ww............
00000210: 0080 0080 0080 0080 000a 0000 0000 0000 ................
00000220: 0400 0000 0000 0000 0000 0000 0002 0000 ................
00000240: c440 b354 9810 2200 0000 0000 0000 0000 .@.T..".........
00000300: 0000 0000 0000 0000 0000 0000 0200 0000 ................
00000320: 0100 0000 0000 0000 0000 0000 0000 0000 ................
00000400: 001c f800 0000 0000 0001 1b14 0316 0000 ................
00000410: 0000 0080 0080 0000 0000 0000 0000 0000 ................
00000600: 0100 0000 0000 0000 0000 0000 0000 0000 ................
00000700: 028a ef00 0000 0000 0000 0000 0000 0000 ................
00000720: 0000 ffc0 0a03 0a00 0100 0010 00ff 0000 ................
00000730: 0000 0014 0000 0000 0000 0000 0000 0000 ................
00002000: 0000 0000 0002 0000 0008 0000 7777 0101 ............ww..
Thanks a lot for looking into this!</pre>
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