Your message dated Wed, 15 Oct 2025 13:17:46 +0100
with message-id <[email protected]>
and subject line Re: Bug#884100: gnome-settings-daemon: backlight control
broken on recent laptops with hybrid graphics
has caused the Debian Bug report #884100,
regarding gnome-settings-daemon: backlight control broken on recent laptops
with hybrid graphics
to be marked as done.
This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.
(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact [email protected]
immediately.)
--
884100: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=884100
Debian Bug Tracking System
Contact [email protected] with problems
--- Begin Message ---
Package: gnome-settings-daemon
Version: 3.22.2-2+deb9u2
Severity: important
Tags: patch stretch
Fixed: 3.24
Forwarded: https://bugzilla.gnome.org/show_bug.cgi?id=782211
Dear Maintainer,
On a brand-new Dell Precision 7520 with hybrid graphics (Intel iGPU +
AMD dGPU) gsd-backlight-helper changes the wrong brightness control -
it tries to modify the AMD dGPU sysfs value, which does not actually
control the screen:
$ ls /sys/class/backlight/
amdgpu_bl0 intel_backlight
gsd writes to amdgpu_bl0 instead of intel_backlight. Note that I've
tried numerous kernel command line workarounds that I found related to
brightness control issues, including:
video.use_bios_initial_backlight=0
video.use_native_backlight=1
acpi_osi="!Windows 2012"
acpi_osi="!Windows 2009"
video.use_native_backlight=0
acpi_backlight=video/vendor/native/none
And also a newer kernel from stretch-backports. None of this fixes the
problem.
But this bug has been fixed upstream, in the mentioned bugzilla.
The patch is quite simple, it applies cleanly to 3.22, I've tested it
and it fixes the problem for me - with the change, the screen
brightness controls function as expected.
Please consider this patch for the next Stretch point release if
possible.
Thanks!
--
Kind regards,
Luca Boccassi
From ed7c2744aca1ad0bdd5adb62a8f2b5bdc1eb94b4 Mon Sep 17 00:00:00 2001
From: Hans de Goede <[email protected]>
Date: Mon, 8 May 2017 15:07:18 +0200
Subject: [PATCH] power: Choose correct backlight device on laptops with
hybrid graphics
On laptops with hybrid graphics the LCD panel may be connected to
a mux so that it can be driven by either GPU. In this case both
GPU drivers will register a raw backlight interface for their
LCD panel connector and g-s-d needs to pick the one for the enabled
connector rather then just picking the first one.
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1683445
https://bugzilla.gnome.org/show_bug.cgi?id=782211
---
plugins/power/gsd-backlight-linux.c | 36 +++++++++++++++++++++++++++++++++++-
1 file changed, 35 insertions(+), 1 deletion(-)
diff --git a/plugins/power/gsd-backlight-linux.c
b/plugins/power/gsd-backlight-linux.c
index 54d6f9dc..27b56ae9 100644
--- a/plugins/power/gsd-backlight-linux.c
+++ b/plugins/power/gsd-backlight-linux.c
@@ -43,6 +43,40 @@ gsd_backlight_helper_get_type (GList *devices, const gchar
*type)
}
return NULL;
}
+
+/*
+ * Search for a raw backlight interface, raw backlight interfaces registered
+ * by the drm driver will have the drm-connector as their parent, check the
+ * drm-connector's enabled sysfs attribute so that we pick the right LCD-panel
+ * connector on laptops with hybrid-gfx. Fall back to just picking the first
+ * raw backlight interface if no enabled interface is found.
+ */
+static gchar *
+gsd_backlight_helper_get_raw (GList *devices)
+{
+ GUdevDevice *parent;
+ const gchar *attr;
+ GList *d;
+
+ for (d = devices; d != NULL; d = d->next) {
+ attr = g_udev_device_get_sysfs_attr (d->data, "type");
+ if (g_strcmp0 (attr, "raw") != 0)
+ continue;
+
+ parent = g_udev_device_get_parent (d->data);
+ if (!parent)
+ continue;
+
+ attr = g_udev_device_get_sysfs_attr (parent, "enabled");
+ if (!attr || g_strcmp0 (attr, "enabled") != 0)
+ continue;
+
+ return g_strdup (g_udev_device_get_sysfs_path (d->data));
+ }
+
+ return gsd_backlight_helper_get_type (devices, "raw");
+}
+
#endif /* HAVE_GUDEV */
char *
@@ -72,7 +106,7 @@ gsd_backlight_helper_get_best_backlight (GsdBacklightType
*type)
*type = GSD_BACKLIGHT_TYPE_PLATFORM;
goto out;
}
- path = gsd_backlight_helper_get_type (devices, "raw");
+ path = gsd_backlight_helper_get_raw (devices);
if (path != NULL) {
if (type)
*type = GSD_BACKLIGHT_TYPE_RAW;
--
2.14.2
signature.asc
Description: This is a digitally signed message part
--- End Message ---
--- Begin Message ---
Version: 3.25.92-1
On Mon, 11 Dec 2017 at 12:31:05 +0000, Luca Boccassi wrote:
On a brand-new Dell Precision 7520 with hybrid graphics (Intel iGPU +
AMD dGPU) gsd-backlight-helper changes the wrong brightness control
...
this bug has been fixed upstream, in the mentioned bugzilla
This appears to have been fixed in the 3.25.x cycle, and therefore is no
longer relevant in any supported Debian release.
smcv
--- End Message ---
