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<body><span class="vcard"><a class="email" href="mailto:lakshminarayana.vudum@intel.com" title="Lakshmi <lakshminarayana.vudum@intel.com>"> <span class="fn">Lakshmi</span></a>
</span> changed
<a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - ThinkPad X1 Extreme 2nd Generation does not advertise DPCD backlight in vbios"
href="https://bugs.freedesktop.org/show_bug.cgi?id=112376">bug 112376</a>
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<th>What</th>
<th>Removed</th>
<th>Added</th>
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<td style="text-align:right;">CC</td>
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<td>jani.nikula@intel.com
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<td style="text-align:right;">Status</td>
<td>NEW
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<td>NEEDINFO
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<b><a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - ThinkPad X1 Extreme 2nd Generation does not advertise DPCD backlight in vbios"
href="https://bugs.freedesktop.org/show_bug.cgi?id=112376#c1">Comment # 1</a>
on <a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - ThinkPad X1 Extreme 2nd Generation does not advertise DPCD backlight in vbios"
href="https://bugs.freedesktop.org/show_bug.cgi?id=112376">bug 112376</a>
from <span class="vcard"><a class="email" href="mailto:lakshminarayana.vudum@intel.com" title="Lakshmi <lakshminarayana.vudum@intel.com>"> <span class="fn">Lakshmi</span></a>
</span></b>
<pre>(In reply to Lyude Paul from <a href="show_bug.cgi?id=112376#c0">comment #0</a>)
<span class="quote">> Created <span class=""><a href="attachment.cgi?id=146015" name="attach_146015" title="VBIOS">attachment 146015</a> <a href="attachment.cgi?id=146015&action=edit" title="VBIOS">[details]</a></span>
> VBIOS
>
> Filing this at the request of some of the Intel folks. I recently got my
> hand on a ThinkPad X1 Extreme 2nd Generation with the optional 4K AMOLED
> screen, and discovered that backlight controls weren't working. While there
> seems to be multiple problems here, all of which I've come up with some
> patches for that I plan to send out after filing this bug, one of the big
> things I noticed was that despite requiring DPCD backlight control this
> laptop claims to be using PWM backlight controls in it's vbios. So, I'm
> filing this bug to upload the vbios along with DPCD and other relevant
> information here.
>
> As well, here's a dump of some relevant DPCD registers:
>
> [ 3.142168] [drm:intel_dp_read_dpcd [i915]] DPCD: 14 14 c4 01 00 00 01 c0
> 02 14 00 00 00 08 82
> [ 3.142600] [drm:drm_dp_read_desc [drm_kms_helper]] DP sink: OUI ba-41-59
> dev-ID HW-rev 0.0 SW-rev 0.0 quirks 0x0000
> [ 3.143012] [drm:intel_dp_init_connector [i915]] eDP DPCD: 05 9d a6
>
> If you need any more information just let me know and I'll be happy to
> uplaod it</span >
How old is the kernel? Can you attach the full dmesg with kernel parameters
drm.debug=0x1e log_buf_len=4M to see more information about the issue?</pre>
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