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ACPI: video: Allow GPU drivers to report no panels 

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 <hdegoede@redhat.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Mario Limonciello 2022-12-08 10:42:05 -06:00 committed by Rafael J. Wysocki
parent 057b40f43c
commit 00a734104a
2 changed files with 13 additions and 0 deletions
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11
drivers/acpi/acpi_video.c
View File

@ -2176,6 +2176,17 @@ static bool should_check_lcd_flag(void)
return false;
}
/*
* At least one graphics driver has reported that no LCD is connected
* via the native interface. cancel the registration for fallback acpi_video0.
* If another driver still deems this necessary, it can explicitly register it.
*/
void acpi_video_report_nolcd(void)
{
cancel_delayed_work(&video_bus_register_backlight_work);
}
EXPORT_SYMBOL(acpi_video_report_nolcd);
int acpi_video_register(void)
{
int ret = 0;

2
include/acpi/video.h
View File

@ -53,6 +53,7 @@ enum acpi_backlight_type {
};
#if IS_ENABLED(CONFIG_ACPI_VIDEO)
extern void acpi_video_report_nolcd(void);
extern int acpi_video_register(void);
extern void acpi_video_unregister(void);
extern void acpi_video_register_backlight(void);
@ -69,6 +70,7 @@ extern int acpi_video_get_levels(struct acpi_device *device,
struct acpi_video_device_brightness **dev_br,
int *pmax_level);
#else
static inline void acpi_video_report_nolcd(void) { return; };
static inline int acpi_video_register(void) { return -ENODEV; }
static inline void acpi_video_unregister(void) { return; }
static inline void acpi_video_register_backlight(void) { return; }