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authorHans de Goede <hdegoede@redhat.com>2022-04-15 14:59:48 +0300
committerHans de Goede <hdegoede@redhat.com>2022-08-17 13:30:05 +0300
commit2600bfa3df9944562d43d1f17016832a6ffa3b38 (patch)
tree5206d8cc6ea54884b7b434d1c395349c0b34d6d3 /drivers/acpi/video_detect.c
parent568035b01cfb107af8d2e4bd2fb9aea22cf5b868 (diff)
downloadlinux-2600bfa3df9944562d43d1f17016832a6ffa3b38.tar.xz
ACPI: video: Add acpi_video_backlight_use_native() helper
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 <rafael.j.wysocki@intel.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Diffstat (limited to 'drivers/acpi/video_detect.c')
-rw-r--r--drivers/acpi/video_detect.c24
1 files changed, 20 insertions, 4 deletions
diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index 5d7f38016a24..5f105eaa7d30 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -17,8 +17,9 @@
* Otherwise vendor specific drivers like thinkpad_acpi, asus-laptop,
* sony_acpi,... can take care about backlight brightness.
*
- * Backlight drivers can use acpi_video_get_backlight_type() to determine
- * which driver should handle the backlight.
+ * Backlight drivers can use acpi_video_get_backlight_type() to determine which
+ * driver should handle the backlight. RAW/GPU-driver backlight drivers must
+ * use the acpi_video_backlight_use_native() helper for this.
*
* If CONFIG_ACPI_VIDEO is neither set as "compiled in" (y) nor as a module (m)
* this file will not be compiled and acpi_video_get_backlight_type() will
@@ -571,9 +572,10 @@ static int acpi_video_backlight_notify(struct notifier_block *nb,
* Arguably the native on win8 check should be done first, but that would
* be a behavior change, which may causes issues.
*/
-enum acpi_backlight_type acpi_video_get_backlight_type(void)
+static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
{
static DEFINE_MUTEX(init_mutex);
+ static bool native_available;
static bool init_done;
static long video_caps;
@@ -593,6 +595,8 @@ enum acpi_backlight_type acpi_video_get_backlight_type(void)
backlight_notifier_registered = true;
init_done = true;
}
+ if (native)
+ native_available = true;
mutex_unlock(&init_mutex);
if (acpi_backlight_cmdline != acpi_backlight_undef)
@@ -604,13 +608,25 @@ enum acpi_backlight_type acpi_video_get_backlight_type(void)
if (!(video_caps & ACPI_VIDEO_BACKLIGHT))
return acpi_backlight_vendor;
- if (acpi_osi_is_win8() && backlight_device_get_by_type(BACKLIGHT_RAW))
+ if (acpi_osi_is_win8() &&
+ (native_available || backlight_device_get_by_type(BACKLIGHT_RAW)))
return acpi_backlight_native;
return acpi_backlight_video;
}
+
+enum acpi_backlight_type acpi_video_get_backlight_type(void)
+{
+ return __acpi_video_get_backlight_type(false);
+}
EXPORT_SYMBOL(acpi_video_get_backlight_type);
+bool acpi_video_backlight_use_native(void)
+{
+ return __acpi_video_get_backlight_type(true) == acpi_backlight_native;
+}
+EXPORT_SYMBOL(acpi_video_backlight_use_native);
+
/*
* Set the preferred backlight interface type based on DMI info.
* This function allows DMI blacklists to be implemented by external