[PATCH AUTOSEL 6.1 05/10] ACPI: video: Don't enable fallback path for creating ACPI backlight by default

Sasha Levin
2023-01-03T18:40:10Z

From: Mario Limonciello <mario.limonciello@amd.com>

[ Upstream commit 5aa9d943e9b6bf6e6023645cbe7ce7d5ed84baf4 ]

The ACPI video detection code has a module parameter
`register_backlight_delay` which is currently configured to 8 seconds.
This means that if after 8 seconds of booting no native driver has created
a backlight device then the code will attempt to make an ACPI video
backlight device.

This was intended as a safety mechanism with the backlight overhaul that
occurred in kernel 6.1, but as it doesn't appear necesssary set it to be
disabled by default.

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/acpi/acpi_video.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
index f64fdb029090..0c79f463fbfd 100644
--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -70,11 +70,7 @@ module_param(device_id_scheme, bool, 0444);
static int only_lcd = -1;
module_param(only_lcd, int, 0444);

-/*
- * Display probing is known to take up to 5 seconds, so delay the fallback
- * backlight registration by 5 seconds + 3 seconds for some extra margin.
- */
-static int register_backlight_delay = 8;
+static int register_backlight_delay;
module_param(register_backlight_delay, int, 0444);
MODULE_PARM_DESC(register_backlight_delay,
"Delay in seconds before doing fallback (non GPU driver triggered) "
--
2.35.1