kernel/linux.git/include/acpi/video.h, branch v6.18.21

ACPI: video: Add Dell UART backlight controller detection

2024-08-19T13:58:35+00:00

Dell All In One (AIO) models released after 2017 use a backlight controller board connected to an UART. In DSDT this uart port will be defined as: Name (_HID, "DELL0501") Name (_CID, EisaId ("PNP0501") Commit 484bae9e4d6a ("platform/x86: Add new Dell UART backlight driver") has added support for this, but I neglected to tie this into acpi_video_get_backlight_type(). Now the first AIO has turned up which has not only the DSDT bits for this, but also an actual controller attached to the UART, yet it is not using this controller for backlight control. Add support to acpi_video_get_backlight_type() for a new dell_uart backlight type. So that the existing infra to override the backlight control method on the commandline or with DMI quirks can be used. Fixes: 484bae9e4d6a ("platform/x86: Add new Dell UART backlight driver") Cc: All applicable Signed-off-by: Hans de Goede Reviewed-by: Andy Shevchenko Link: https://patch.msgid.link/20240814190159.15650-2-hdegoede@redhat.com Signed-off-by: Rafael J. Wysocki

ACPI: video: Add comment about acpi_video_backlight_use_native() usage

2023-11-20T16:47:07+00:00

Add a comment explaining that acpi_video_backlight_use_native() MUST only be used by GPU drivers and that it must NOT be used on other places. Signed-off-by: Hans de Goede Signed-off-by: Rafael J. Wysocki

ACPI: video: Remove register_backlight_delay module option and code

2023-04-11T18:55:46+00:00

Since commit 5aa9d943e9b6 ("ACPI: video: Don't enable fallback path for creating ACPI backlight by default"), the delayed registering of acpi_video# backlight devices has been disabled by default. The few bugreports where this option was used as a workaround were all cases where the GPU driver did not call acpi_video_register_backlight() and the workaround was to pass video.register_backlight_delay=1. With the recent "ACPI: video: Make acpi_backlight=video work independent from GPU driver" changes acpi_backlight=video can be used to achieve the same result. So there is no need for the register_backlight_delay option + code anymore. Reviewed-by: Mario Limonciello Signed-off-by: Hans de Goede Signed-off-by: Rafael J. Wysocki

ACPI: video: Add auto_detect arg to __acpi_video_get_backlight_type()

2023-04-05T18:23:02+00:00

Allow callers of __acpi_video_get_backlight_type() to pass a pointer to a bool which will get set to false if the backlight-type comes from the cmdline or a DMI quirk and set to true if auto-detection was used. And make __acpi_video_get_backlight_type() non static so that it can be called directly outside of video_detect.c . While at it turn the acpi_video_get_backlight_type() and acpi_video_backlight_use_native() wrappers into static inline functions in include/acpi/video.h, so that we need to export one less symbol. Fixes: 5aa9d943e9b6 ("ACPI: video: Don't enable fallback path for creating ACPI backlight by default") Cc: All applicable Reviewed-by: Mario Limonciello Signed-off-by: Hans de Goede Signed-off-by: Rafael J. Wysocki

ACPI: video: Allow GPU drivers to report no panels

2022-12-22T16:26:41+00:00

The current logic for the ACPI backlight detection will create a backlight device if no native or vendor drivers have created 8 seconds after the system has booted if the ACPI tables included backlight control methods. If the GPU drivers have loaded, they may be able to report whether any LCD panels were found. Allow using this information to factor in whether to enable the fallback logic for making an acpi_video0 backlight device. Suggested-by: Hans de Goede Signed-off-by: Mario Limonciello Reviewed-by: Hans de Goede Signed-off-by: Rafael J. Wysocki

ACPI: video: Remove acpi_video_set_dmi_backlight_type()

2022-09-03T10:17:27+00:00

acpi_video_set_dmi_backlight_type() is troublesome because it may end up getting called after other backlight drivers have already called acpi_video_get_backlight_type() resulting in the other drivers already being registered even though they should not. In case of the acpi_video backlight, acpi_video_set_dmi_backlight_type() actually calls acpi_video_unregister_backlight() since that is often probed earlier, leading to userspace seeing the acpi_video0 class device being briefly available, leading to races in userspace where udev probe-rules try to access the device and it is already gone. All callers have been fixed to no longer call it, so remove acpi_video_set_dmi_backlight_type() now. This means we now also no longer need acpi_video_unregister_backlight() for the remove acpi_video backlight after it was wrongly registered hack, so remove that too. Acked-by: Rafael J. Wysocki Signed-off-by: Hans de Goede

ACPI: video: Add Apple GMUX brightness control detection

2022-09-03T10:17:26+00:00

On Apple laptops with an Apple GMUX using this for brightness control, should take precedence of any other brightness control methods. Add apple-gmux detection to acpi_video_get_backlight_type() using the already existing apple_gmux_present() helper function. This will allow removig the (ab)use of: acpi_video_set_dmi_backlight_type(acpi_backlight_vendor); Inside the apple-gmux driver. Acked-by: Rafael J. Wysocki Signed-off-by: Hans de Goede

ACPI: video: Add Nvidia WMI EC brightness control detection (v3)

2022-09-03T10:17:26+00:00

On some new laptop designs a new Nvidia specific WMI interface is present which gives info about panel brightness control and may allow controlling the brightness through this interface when the embedded controller is used for brightness control. When this WMI interface is present and indicates that the EC is used, then this interface should be used for brightness control. Changes in v2: - Use the new shared nvidia-wmi-ec-backlight.h header for the WMI firmware API definitions - ACPI_VIDEO can now be enabled on non X86 too, adjust the Kconfig changes to match this. Changes in v3: - Use WMI_BRIGHTNESS_GUID define Acked-by: Rafael J. Wysocki Reviewed-by: Daniel Dadap Signed-off-by: Hans de Goede

ACPI: video: Make backlight class device registration a separate step (v2)

2022-09-02T07:57:14+00:00

On x86/ACPI boards the acpi_video driver will usually initialize before the kms driver (except i915). This causes /sys/class/backlight/acpi_video0 to show up and then the kms driver registers its own native backlight device after which the drivers/acpi/video_detect.c code unregisters the acpi_video0 device (when acpi_video_get_backlight_type()==native). This means that userspace briefly sees 2 devices and the disappearing of acpi_video0 after a brief time confuses the systemd backlight level save/restore code, see e.g.: https://bbs.archlinux.org/viewtopic.php?id=269920 To fix this make backlight class device registration a separate step done by a new acpi_video_register_backlight() function. The intend is for this to be called by the drm/kms driver *after* it is done setting up its own native backlight device. So that acpi_video_get_backlight_type() knows if a native backlight will be available or not at acpi_video backlight registration time, avoiding the add + remove dance. Note the new acpi_video_register_backlight() function is also called from a delayed work to ensure that the acpi_video backlight devices does get registered if necessary even if there is no drm/kms driver or when it is disabled. Changes in v2: - Make register_backlight_delay a module parameter, mainly so that it can be disabled by Nvidia binary driver users Acked-by: Rafael J. Wysocki Signed-off-by: Hans de Goede

ACPI: video: Add acpi_video_backlight_use_native() helper

2022-08-17T10:30:05+00:00

ATM on x86 laptops where we want userspace to use the acpi_video backlight device we often register both the GPU's native backlight device and acpi_video's firmware acpi_video# backlight device. This relies on userspace preferring firmware type backlight devices over native ones, but registering 2 backlight devices for a single display really is undesirable. On x86 laptops where the native GPU backlight device should be used, the registering of other backlight devices is avoided by their drivers using acpi_video_get_backlight_type() and only registering their backlight if the return value matches their type. acpi_video_get_backlight_type() uses backlight_device_get_by_type(BACKLIGHT_RAW) to determine if a native driver is available and will never return native if this returns false. This means that the GPU's native backlight registering code cannot just call acpi_video_get_backlight_type() to determine if it should register its backlight, since acpi_video_get_backlight_type() will never return native until the native backlight has already registered. To fix this add a new internal native function parameter to acpi_video_get_backlight_type(), which when set to true will make acpi_video_get_backlight_type() behave as if a native backlight has already been registered. And add a new acpi_video_backlight_use_native() helper, which sets this to true, for use in native GPU backlight code. Changes in v2: - Replace adding a native parameter to acpi_video_get_backlight_type() with adding a new acpi_video_backlight_use_native() helper. Acked-by: Rafael J. Wysocki Signed-off-by: Hans de Goede