This is a note to let you know that I've just added the patch titled
ACPI: video: Make acpi_backlight=video work independent from GPU driver
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
acpi-video-make-acpi_backlight-video-work-independent-from-gpu-driver.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e506731c8f35699d746c615164ed620cd53c00ca Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede@xxxxxxxxxx>
Date: Tue, 4 Apr 2023 13:02:47 +0200
Subject: ACPI: video: Make acpi_backlight=video work independent from GPU driver
From: Hans de Goede <hdegoede@xxxxxxxxxx>
commit e506731c8f35699d746c615164ed620cd53c00ca upstream.
Commit 3dbc80a3e4c5 ("ACPI: video: Make backlight class device
registration a separate step (v2)") combined with
commit 5aa9d943e9b6 ("ACPI: video: Don't enable fallback path for
creating ACPI backlight by default")
Means that the video.ko code now fully depends on the GPU driver calling
acpi_video_register_backlight() for the acpi_video# backlight class
devices to get registered.
This means that if the GPU driver does not do this, acpi_backlight=video
on the cmdline, or DMI quirks for selecting acpi_video# will not work.
This is a problem on for example Apple iMac14,1 all-in-ones where
the monitor's LCD panel shows up as a regular DP connection instead of
eDP so the GPU driver will not call acpi_video_register_backlight() [1].
Fix this by making video.ko directly register the acpi_video# devices
when these have been explicitly requested either on the cmdline or
through DMI quirks (rather then auto-detection being used).
[1] GPU drivers only call acpi_video_register_backlight() when an internal
panel is detected, to avoid non working acpi_video# devices getting
registered on desktops which unfortunately is a real issue.
Fixes: 5aa9d943e9b6 ("ACPI: video: Don't enable fallback path for creating ACPI backlight by default")
Cc: All applicable <stable@xxxxxxxxxxxxxxx>
Reviewed-by: Mario Limonciello <mario.limonciello@xxxxxxx>
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/acpi/acpi_video.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -1984,6 +1984,7 @@ static int instance;
static int acpi_video_bus_add(struct acpi_device *device)
{
struct acpi_video_bus *video;
+ bool auto_detect;
int error;
acpi_status status;
@@ -2045,10 +2046,20 @@ static int acpi_video_bus_add(struct acp
mutex_unlock(&video_list_lock);
/*
- * The userspace visible backlight_device gets registered separately
- * from acpi_video_register_backlight().
+ * If backlight-type auto-detection is used then a native backlight may
+ * show up later and this may change the result from video to native.
+ * Therefor normally the userspace visible /sys/class/backlight device
+ * gets registered separately by the GPU driver calling
+ * acpi_video_register_backlight() when an internal panel is detected.
+ * Register the backlight now when not using auto-detection, so that
+ * when the kernel cmdline or DMI-quirks are used the backlight will
+ * get registered even if acpi_video_register_backlight() is not called.
*/
acpi_video_run_bcl_for_osi(video);
+ if (__acpi_video_get_backlight_type(false, &auto_detect) == acpi_backlight_video &&
+ !auto_detect)
+ acpi_video_bus_register_backlight(video);
+
acpi_video_bus_add_notify_handler(video);
return 0;
Patches currently in stable-queue which might be from hdegoede@xxxxxxxxxx are
queue-6.1/platform-x86-think-lmi-clean-up-display-of-current_v.patch
queue-6.1/platform-x86-think-lmi-fix-memory-leak-when-showing-.patch
queue-6.1/wifi-brcmfmac-fix-sdio-suspend-resume-regression.patch
queue-6.1/platform-x86-think-lmi-fix-memory-leaks-when-parsing.patch
queue-6.1/acpi-video-add-auto_detect-arg-to-__acpi_video_get_backlight_type.patch
queue-6.1/acpi-video-add-acpi_backlight-video-quirk-for-apple-imac14-1-and-imac14-2.patch
queue-6.1/serial-8250-prevent-starting-up-dma-rx-on-thri-interrupt.patch
queue-6.1/iio-light-cm32181-unregister-second-i2c-client-if-present.patch
queue-6.1/acpi-video-add-acpi_backlight-video-quirk-for-lenovo-thinkpad-w530.patch
queue-6.1/acpi-video-make-acpi_backlight-video-work-independent-from-gpu-driver.patch
