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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 - Laptop Backlight Issue with Hybrid Graphics System"
href="https://bugs.freedesktop.org/show_bug.cgi?id=90151">90151</a>
</td>
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<th>Summary</th>
<td>Laptop Backlight Issue with Hybrid Graphics System
</td>
</tr>
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<th>Product</th>
<td>xorg
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
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<th>OS</th>
<td>Linux (All)
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<th>Status</th>
<td>NEW
</td>
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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>Driver/Radeon
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<th>Assignee</th>
<td>xorg-driver-ati@lists.x.org
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<th>Reporter</th>
<td>k.sarendranath@gmail.com
</td>
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<th>QA Contact</th>
<td>xorg-team@lists.x.org
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</tr></table>
<p>
<div>
<pre>Kernel Version: 3.19.3
Radeon Version: 1:7.5.0-2
Xorg Verison: 1.17.1-5
The system being used is a Lenovo Thinkpad configured with an R7 M260DX
discrete card attached to an A10-7300. Upon booting it, the kernel spits out
this message:
[drm:radeon_acpi_init [radeon]] *ERROR* Cannot find a backlight controller
with the quirk of having the brightness hotkeys not being able to control the
brightness. Looking into the radeon source, here is where the call came from
(radeon_acpi.c):
atif->encoder_for_bl = target;
if (!target) {
/* Brightness change notification is enabled, but we
* didn't find a backlight controller, this should
* never happen.
*/
DRM_ERROR("Cannot find a backlight controller\n");
}
Is this an issue within the driver or from Lenovo's acpi implementation?
If anything, I can control the backlight by using the /sys/ subsystem so I can
remap the hotkeys to control the brightness while systemd will store it on
reboot. In essence, I just wanted to bring this to attention due to the comment
in the source.
Also a quick question on hybrid graphics, the radeon feature matrix states that
Enduro is mostly complete and I believe that this lenovo system is muxless.
Checking vgaswitcheroo, the integrated card is used while the discrete card is
"DynOff" which I presume is dynamically off. Does that mean the driver is
currently powering on the discrete card when rendering is required? Or is
something else required?
Thanks for any answers.</pre>
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