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![Hans de Goede](/assets/img/avatar_default.png)
Add an acpi_video_unregister_backlight function, which only unregisters the backlight device, and leaves the acpi_notifier in place. Some acpi_vendor driver need this as they don't want the acpi_video# backlight device, but do need the acpi-video driver for hotkey handling. Chances are that this new acpi_video_unregister_backlight() is actually what existing acpi_vendor drivers have wanted all along. Currently acpi_vendor drivers which want to disable the acpi_video# backlight device, make 2 calls: acpi_video_dmi_promote_vendor(); acpi_video_unregister(); The intention here is to make things independent of when acpi_video_register() gets called. As acpi_video_register() will get called on acpi-video load time on non intel gfx machines, while it gets called on i915 load time on intel gfx machines. This leads to the following 2 interesting scenarios: a) intel gfx: 1) acpi-video module gets loaded (as it is a dependency of acpi_vendor and i915) 2) acpi-video does NOT call acpi_video_register() 3) acpi_vendor loads (lets assume it loads before i915), calls acpi_video_dmi_promote_vendor(); which sets ACPI_VIDEO_BACKLIGHT_DMI_VENDOR 4) calls acpi_video_unregister -> not registered, nop 5) i915 loads, calls acpi_video_register 6) acpi_video_register registers the acpi_notifier for the hotkeys, does NOT register a backlight device because of ACPI_VIDEO_BACKLIGHT_DMI_VENDOR b) non intel gfx 1) acpi-video module gets loaded (as it is a dependency acpi_vendor) 2) acpi-video calls acpi_video_register() 3) acpi_video_register registers the acpi_notifier for the hotkeys, and a backlight device 4) acpi_vendor loads, calls acpi_video_dmi_promote_vendor() 5) calls acpi_video_unregister, this unregisters BOTH the acpi_notifier for the hotkeys AND the backlight device So here we have possibly the same acpi_vendor module, making the same calls, but with different results, in one cases acpi-video does handle hotkeys, in the other it does not. Note that the a) scenario turns into b) if we assume the i915 module loads before the vendor_acpi module, so we also have different behavior depending on module loading order! So as said I believe that quite a few existing acpi_vendor modules really always want the behavior of a), hence this patch adds a new acpi_video_unregister_backlight() which gives the behavior of a) independent of module loading order. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
36 lines
1.1 KiB
C
36 lines
1.1 KiB
C
#ifndef __ACPI_VIDEO_H
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#define __ACPI_VIDEO_H
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#include <linux/errno.h> /* for ENODEV */
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struct acpi_device;
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#define ACPI_VIDEO_CLASS "video"
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#define ACPI_VIDEO_DISPLAY_CRT 1
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#define ACPI_VIDEO_DISPLAY_TV 2
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#define ACPI_VIDEO_DISPLAY_DVI 3
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#define ACPI_VIDEO_DISPLAY_LCD 4
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#define ACPI_VIDEO_DISPLAY_LEGACY_MONITOR 0x0100
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#define ACPI_VIDEO_DISPLAY_LEGACY_PANEL 0x0110
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#define ACPI_VIDEO_DISPLAY_LEGACY_TV 0x0200
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#if (defined CONFIG_ACPI_VIDEO || defined CONFIG_ACPI_VIDEO_MODULE)
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extern int acpi_video_register(void);
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extern void acpi_video_unregister(void);
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extern void acpi_video_unregister_backlight(void);
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extern int acpi_video_get_edid(struct acpi_device *device, int type,
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int device_id, void **edid);
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#else
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static inline int acpi_video_register(void) { return 0; }
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static inline void acpi_video_unregister(void) { return; }
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static inline void acpi_video_unregister_backlight(void) { return; }
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static inline int acpi_video_get_edid(struct acpi_device *device, int type,
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int device_id, void **edid)
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{
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return -ENODEV;
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}
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#endif
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#endif
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