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ACPI / video: Add a acpi_video_handles_brightness_key_presses() helper

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Several drivers want to know if the acpi-video is generating key-presses
for brightness change hotkeys to avoid sending double key-events to
userspace for these. Currently these driver use this construct for this:

	if (acpi_video_get_backlight_type() == acpi_backlight_vendor)
		report_brightness_key_event();

This indirect way of detecting if acpi-video is active does not make the
code easier to understand, and in some cases it is wrong because just
because the preferred type != vendor does not mean that acpi-video is
actually listening for brightness events, e.g. there may be no acpi-video
bus on the system at all.

This commit adds a acpi_video_handles_brightness_key_presses() helper
function, making the code needing this functionality both easier to read
and more correct.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Hans de Goede 2015-12-22 19:09:48 +01:00 committed by Rafael J. Wysocki
parent 74bf8efb5f
commit 90b066b15e
2 changed files with 18 additions and 0 deletions
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12
drivers/acpi/acpi_video.c
View file

@ -2072,6 +2072,18 @@ void acpi_video_unregister_backlight(void)
mutex_unlock(&register_count_mutex);
}
bool acpi_video_handles_brightness_key_presses(void)
{
bool have_video_busses;
mutex_lock(&video_list_lock);
have_video_busses = !list_empty(&video_bus_head);
mutex_unlock(&video_list_lock);
return have_video_busses;
}
EXPORT_SYMBOL(acpi_video_handles_brightness_key_presses);
/*
* This is kind of nasty. Hardware using Intel chipsets may require
* the video opregion code to be run first in order to initialise

6
include/acpi/video.h
View file

@ -2,6 +2,7 @@
#define __ACPI_VIDEO_H
#include <linux/errno.h> /* for ENODEV */
#include <linux/types.h> /* for bool */
struct acpi_device;
@ -31,6 +32,7 @@ extern int acpi_video_get_edid(struct acpi_device *device, int type,
int device_id, void **edid);
extern enum acpi_backlight_type acpi_video_get_backlight_type(void);
extern void acpi_video_set_dmi_backlight_type(enum acpi_backlight_type type);
extern bool acpi_video_handles_brightness_key_presses(void);
#else
static inline int acpi_video_register(void) { return 0; }
static inline void acpi_video_unregister(void) { return; }
@ -46,6 +48,10 @@ static inline enum acpi_backlight_type acpi_video_get_backlight_type(void)
static inline void acpi_video_set_dmi_backlight_type(enum acpi_backlight_type type)
{
}
static inline bool acpi_video_handles_brightness_key_presses(void)
{
return false;
}
#endif
#endif