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authorHans de Goede <hdegoede@redhat.com>2023-03-07 13:05:40 +0100
committerHans de Goede <hdegoede@redhat.com>2023-03-16 13:33:11 +0100
commit3608a2cd818a8d97bd3d4dc32f6c0afaf09b15ec (patch)
tree456d6791cc25e151b40b9471bd7be489e6f8fdce
parentf0f2903de50418899a5e5dcecf2906da44a7a05e (diff)
backlight: apple_bl: Use acpi_video_get_backlight_type()
On some MacBooks both the apple_bl and the apple-gmux backlight drivers may be able to export a /sys/class/backlight device. To avoid having 2 backlight devices for one LCD panel until now the apple-gmux driver has been calling apple_bl_unregister() to move the apple_bl backlight device out of the way when it loads. Similar problems exist on other x86 laptops and all backlight drivers which may be used on x86 laptops have moved to using acpi_video_get_backlight_type() to determine whether they should load or not. Switch apple_bl to this model too, so that it is consistent with all the other x86 backlight drivers. Besides code-simplification and consistency this has 2 other benefits: 1) It removes a race during boot where userspace will briefly see an apple_bl backlight and then have it disappear again, leading to e.g.: https://bbs.archlinux.org/viewtopic.php?id=269920 2) This allows user to switch between the drivers by passing acpi_backlight=apple_gmux or acpi_backlight=vendor on the kernel commandline. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Acked-by: Lee Jones <lee@kernel.org> Link: https://lore.kernel.org/r/20230307120540.389920-1-hdegoede@redhat.com
-rw-r--r--drivers/platform/x86/Kconfig1
-rw-r--r--drivers/platform/x86/apple-gmux.c11
-rw-r--r--drivers/video/backlight/Kconfig1
-rw-r--r--drivers/video/backlight/apple_bl.c31
-rw-r--r--include/linux/apple_bl.h27
5 files changed, 11 insertions, 60 deletions
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index ec7c2b4e1721..1b3189d6e8d2 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -213,7 +213,6 @@ config APPLE_GMUX
depends on ACPI && PCI
depends on PNP
depends on BACKLIGHT_CLASS_DEVICE
- depends on BACKLIGHT_APPLE=n || BACKLIGHT_APPLE
help
This driver provides support for the gmux device found on many
Apple laptops, which controls the display mux for the hybrid
diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index 8aa81a3517b1..4c311e1dedad 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -16,7 +16,6 @@
#include <linux/backlight.h>
#include <linux/acpi.h>
#include <linux/pnp.h>
-#include <linux/apple_bl.h>
#include <linux/apple-gmux.h>
#include <linux/slab.h>
#include <linux/delay.h>
@@ -883,14 +882,6 @@ get_version:
gmux_data->bdev = bdev;
bdev->props.brightness = gmux_get_brightness(bdev);
backlight_update_status(bdev);
-
- /*
- * The backlight situation on Macs is complicated. If the gmux is
- * present it's the best choice, because it always works for
- * backlight control and supports more levels than other options.
- * Disable the other backlight choices.
- */
- apple_bl_unregister();
}
gmux_data->power_state = VGA_SWITCHEROO_ON;
@@ -1007,8 +998,6 @@ static void gmux_remove(struct pnp_dev *pnp)
release_region(gmux_data->iostart, gmux_data->iolen);
apple_gmux_data = NULL;
kfree(gmux_data);
-
- apple_bl_register();
}
static const struct pnp_device_id gmux_device_ids[] = {
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 4c33e971c0f0..51387b1ef012 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -285,6 +285,7 @@ config BACKLIGHT_MT6370
config BACKLIGHT_APPLE
tristate "Apple Backlight Driver"
depends on X86 && ACPI
+ depends on ACPI_VIDEO=n || ACPI_VIDEO
help
If you have an Intel-based Apple say Y to enable a driver for its
backlight.
diff --git a/drivers/video/backlight/apple_bl.c b/drivers/video/backlight/apple_bl.c
index e9e7acb577bf..aaa824437a2a 100644
--- a/drivers/video/backlight/apple_bl.c
+++ b/drivers/video/backlight/apple_bl.c
@@ -24,7 +24,7 @@
#include <linux/pci.h>
#include <linux/acpi.h>
#include <linux/atomic.h>
-#include <linux/apple_bl.h>
+#include <acpi/video.h>
static struct backlight_device *apple_backlight_device;
@@ -215,32 +215,21 @@ static struct acpi_driver apple_bl_driver = {
},
};
-static atomic_t apple_bl_registered = ATOMIC_INIT(0);
-
-int apple_bl_register(void)
-{
- if (atomic_xchg(&apple_bl_registered, 1) == 0)
- return acpi_bus_register_driver(&apple_bl_driver);
-
- return 0;
-}
-EXPORT_SYMBOL_GPL(apple_bl_register);
-
-void apple_bl_unregister(void)
-{
- if (atomic_xchg(&apple_bl_registered, 0) == 1)
- acpi_bus_unregister_driver(&apple_bl_driver);
-}
-EXPORT_SYMBOL_GPL(apple_bl_unregister);
-
static int __init apple_bl_init(void)
{
- return apple_bl_register();
+ /*
+ * Use ACPI video detection code to see if this driver should register
+ * or if another driver, e.g. the apple-gmux driver should be used.
+ */
+ if (acpi_video_get_backlight_type() != acpi_backlight_vendor)
+ return -ENODEV;
+
+ return acpi_bus_register_driver(&apple_bl_driver);
}
static void __exit apple_bl_exit(void)
{
- apple_bl_unregister();
+ acpi_bus_unregister_driver(&apple_bl_driver);
}
module_init(apple_bl_init);
diff --git a/include/linux/apple_bl.h b/include/linux/apple_bl.h
deleted file mode 100644
index 445af2e3cc21..000000000000
--- a/include/linux/apple_bl.h
+++ /dev/null
@@ -1,27 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * apple_bl exported symbols
- */
-
-#ifndef _LINUX_APPLE_BL_H
-#define _LINUX_APPLE_BL_H
-
-#if defined(CONFIG_BACKLIGHT_APPLE) || defined(CONFIG_BACKLIGHT_APPLE_MODULE)
-
-extern int apple_bl_register(void);
-extern void apple_bl_unregister(void);
-
-#else /* !CONFIG_BACKLIGHT_APPLE */
-
-static inline int apple_bl_register(void)
-{
- return 0;
-}
-
-static inline void apple_bl_unregister(void)
-{
-}
-
-#endif /* !CONFIG_BACKLIGHT_APPLE */
-
-#endif /* _LINUX_APPLE_BL_H */