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Commit 87521e16 authored by Hans de Goede's avatar Hans de Goede Committed by Rafael J. Wysocki
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acpi-video-detect: Rewrite backlight interface selection logic 



Currently we have 2 kernel commandline options + dmi-quirks in 3 places all
interacting (in interesting ways) to select which which backlight interface
to use. On the commandline we've acpi_backlight=[video|vendor] and
video.use_native_backlight=[0|1]. DMI quirks we have in
acpi/video-detect.c, acpi/video.c and drivers/platform/x86/*.c .

This commit is the first step to cleaning this up, replacing the 2 cmdline
options with just acpi_backlight=[video|vendor|native|none], and adds a
new API to video_detect.c to reflect this.

Follow up commits will also move other related code, like unregistering the
acpi_video backlight interface if it was registered before other drivers
which take priority over it are loaded, to video_detect.c where this
logic really belongs.

Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Acked-by: default avatarDarren Hart <dvhart@linux.intel.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 14ca7a47

drivers/acpi/video_detect.c

+83 −88
Original line number Diff line number Diff line 
/*

 *  Copyright (C) 2015       Red Hat Inc.

 *                           Hans de Goede <hdegoede@redhat.com>

 *  Copyright (C) 2008       SuSE Linux Products GmbH

 *                           Thomas Renninger <trenn@suse.de>

 *
@@ -9,44 +11,45 @@ 
 * acpi_get_pci_dev() can be called to identify ACPI graphics

 * devices for which a real graphics card is plugged in

 *

 * Now acpi_video_get_capabilities() can be called to check which

 * capabilities the graphics cards plugged in support. The check for general

 * video capabilities will be triggered by the first caller of

 * acpi_video_get_capabilities(NULL); which will happen when the first

 * backlight switching supporting driver calls:

 * acpi_video_backlight_support();

 *

 * Depending on whether ACPI graphics extensions (cmp. ACPI spec Appendix B)

 * are available, video.ko should be used to handle the device.

 *

 * Otherwise vendor specific drivers like thinkpad_acpi, asus-laptop,

 * sony_acpi,... can take care about backlight brightness.

 *

 * If CONFIG_ACPI_VIDEO is neither set as "compiled in" (y) nor as a module (m)

 * this file will not be compiled, acpi_video_get_capabilities() and

 * acpi_video_backlight_support() will always return 0 and vendor specific

 * drivers always can handle backlight.

 * Backlight drivers can use acpi_video_get_backlight_type() to determine

 * which driver should handle the backlight.

 *

 * If CONFIG_ACPI_VIDEO is neither set as "compiled in" (y) nor as a module (m)

 * this file will not be compiled and acpi_video_get_backlight_type() will

 * always return acpi_backlight_vendor.

 */



#include <linux/export.h>

#include <linux/acpi.h>

#include <linux/backlight.h>

#include <linux/dmi.h>

#include <linux/module.h>

#include <linux/pci.h>

#include <linux/types.h>

#include <acpi/video.h>



ACPI_MODULE_NAME("video");

#define _COMPONENT		ACPI_VIDEO_COMPONENT



static long acpi_video_support;

static bool acpi_video_caps_checked;

static enum acpi_backlight_type acpi_backlight_cmdline = acpi_backlight_undef;

static enum acpi_backlight_type acpi_backlight_dmi = acpi_backlight_undef;



static void acpi_video_parse_cmdline(void)

{

	if (!strcmp("vendor", acpi_video_backlight_string))

		acpi_video_support |= ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR;

		acpi_backlight_cmdline = acpi_backlight_vendor;

	if (!strcmp("video", acpi_video_backlight_string))

		acpi_video_support |= ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO;

		acpi_backlight_cmdline = acpi_backlight_video;

	if (!strcmp("native", acpi_video_backlight_string))

		acpi_backlight_cmdline = acpi_backlight_native;

	if (!strcmp("none", acpi_video_backlight_string))

		acpi_backlight_cmdline = acpi_backlight_none;

}



static acpi_status
@@ -77,7 +80,7 @@ find_video(acpi_handle handle, u32 lvl, void *context, void **rv) 
 * buggy */

static int video_detect_force_vendor(const struct dmi_system_id *d)

{

	acpi_video_support |= ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;

	acpi_backlight_dmi = acpi_backlight_vendor;

	return 0;

}
@@ -125,99 +128,91 @@ static const struct dmi_system_id video_detect_dmi_table[] = { 
};



/*

 * Returns the video capabilities of a specific ACPI graphics device

 * Determine which type of backlight interface to use on this system,

 * First check cmdline, then dmi quirks, then do autodetect.

 *

 * if NULL is passed as argument all ACPI devices are enumerated and

 * all graphics capabilities of physically present devices are

 * summarized and returned. This is cached and done only once.

 */

static long acpi_video_get_capabilities(acpi_handle graphics_handle)

{

	long caps = 0;

	struct acpi_device *tmp_dev;

	acpi_status status;



	if (acpi_video_caps_checked && graphics_handle == NULL)

		return acpi_video_support;



	if (!graphics_handle) {

		/* Only do the global walk through all graphics devices once */

		acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,

				    ACPI_UINT32_MAX, find_video, NULL,

				    &caps, NULL);

		/* There might be boot param flags set already... */

		acpi_video_support |= caps;

		acpi_video_caps_checked = 1;

		/* Add blacklists here. Be careful to use the right *DMI* bits

		 * to still be able to override logic via boot params, e.g.:

 * The autodetect order is:

 * 1) Is the acpi-video backlight interface supported ->

 *  no, use a vendor interface

 * 2) Is this a win8 "ready" BIOS and do we have a native interface ->

 *  yes, use a native interface

 * 3) Else use the acpi-video interface

 *

		 *   if (dmi_name_in_vendors("XY")) {

		 *	acpi_video_support |=

		 *		ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;

		 *}

 * Arguably the native on win8 check should be done first, but that would

 * be a behavior change, which may causes issues.

 */

enum acpi_backlight_type acpi_video_get_backlight_type(void)

{

	static DEFINE_MUTEX(init_mutex);

	static bool init_done;

	static long video_caps;



	/* Parse cmdline, dmi and acpi only once */

	mutex_lock(&init_mutex);

	if (!init_done) {

		acpi_video_parse_cmdline();

		dmi_check_system(video_detect_dmi_table);

	} else {

		status = acpi_bus_get_device(graphics_handle, &tmp_dev);

		if (ACPI_FAILURE(status)) {

			ACPI_EXCEPTION((AE_INFO, status, "Invalid device"));

			return 0;

		}

		acpi_walk_namespace(ACPI_TYPE_DEVICE, graphics_handle,

		acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,

				    ACPI_UINT32_MAX, find_video, NULL,

				    &caps, NULL);

				    &video_caps, NULL);

		init_done = true;

	}

	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "We have 0x%lX video support %s %s\n",

			  graphics_handle ? caps : acpi_video_support,

			  graphics_handle ? "on device " : "in general",

			  graphics_handle ? acpi_device_bid(tmp_dev) : ""));

	return caps;

	mutex_unlock(&init_mutex);



	if (acpi_backlight_cmdline != acpi_backlight_undef)

		return acpi_backlight_cmdline;



	if (acpi_backlight_dmi != acpi_backlight_undef)

		return acpi_backlight_dmi;



	if (!(video_caps & ACPI_VIDEO_BACKLIGHT))

		return acpi_backlight_vendor;



	if (acpi_osi_is_win8() && backlight_device_registered(BACKLIGHT_RAW))

		return acpi_backlight_native;



	return acpi_backlight_video;

}

EXPORT_SYMBOL(acpi_video_get_backlight_type);



static void acpi_video_caps_check(void)

{

/*

	 * We must check whether the ACPI graphics device is physically plugged

	 * in. Therefore this must be called after binding PCI and ACPI devices

 * Set the preferred backlight interface type based on DMI info.

 * This function allows DMI blacklists to be implemented by external

 * platform drivers instead of putting a big blacklist in video_detect.c

 */

	if (!acpi_video_caps_checked) {

		acpi_video_parse_cmdline();

		acpi_video_get_capabilities(NULL);

	}

void acpi_video_set_dmi_backlight_type(enum acpi_backlight_type type)

{

	acpi_backlight_dmi = type;

}

EXPORT_SYMBOL(acpi_video_set_dmi_backlight_type);



/* Promote the vendor interface instead of the generic video module.

 * This function allow DMI blacklists to be implemented by externals

 * platform drivers instead of putting a big blacklist in video_detect.c

/*

 * Compatiblity function, this is going away as soon as all drivers are

 * converted to acpi_video_set_dmi_backlight_type().

 *

 * Promote the vendor interface instead of the generic video module.

 * After calling this function you will probably want to call

 * acpi_video_unregister() to make sure the video module is not loaded

 */

void acpi_video_dmi_promote_vendor(void)

{

	acpi_video_caps_check();

	acpi_video_support |= ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;

	acpi_video_set_dmi_backlight_type(acpi_backlight_vendor);

}

EXPORT_SYMBOL(acpi_video_dmi_promote_vendor);



/* Returns true if video.ko can do backlight switching */

/*

 * Compatiblity function, this is going away as soon as all drivers are

 * converted to acpi_video_get_backlight_type().

 *

 * Returns true if video.ko can do backlight switching.

 */

int acpi_video_backlight_support(void)

{

	acpi_video_caps_check();



	/* First check for boot param -> highest prio */

	if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR)

		return 0;

	else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO)

		return 1;



	/* Then check for DMI blacklist -> second highest prio */

	if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VENDOR)

		return 0;

	else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VIDEO)

		return 1;



	/* Then go the default way */

	return acpi_video_support & ACPI_VIDEO_BACKLIGHT;

	/*

	 * This is done this way since vendor drivers call this to see

	 * if they should load, and we do not want them to load for both

	 * the acpi_backlight_video and acpi_backlight_native cases.

	 */

	return acpi_video_get_backlight_type() != acpi_backlight_vendor;

}

EXPORT_SYMBOL(acpi_video_backlight_support);

include/acpi/video.h

+17 −0
Original line number Diff line number Diff line
@@ -16,6 +16,14 @@ struct acpi_device; 
#define ACPI_VIDEO_DISPLAY_LEGACY_PANEL   0x0110

#define ACPI_VIDEO_DISPLAY_LEGACY_TV      0x0200



enum acpi_backlight_type {

	acpi_backlight_undef = -1,

	acpi_backlight_none = 0,

	acpi_backlight_video,

	acpi_backlight_vendor,

	acpi_backlight_native,

};



#if (defined CONFIG_ACPI_VIDEO || defined CONFIG_ACPI_VIDEO_MODULE)

extern int acpi_video_register(void);

extern void acpi_video_unregister(void);
@@ -23,6 +31,8 @@ extern void acpi_video_unregister_backlight(void); 
extern int acpi_video_get_edid(struct acpi_device *device, int type,

			       int device_id, void **edid);

extern bool acpi_video_verify_backlight_support(void);

extern enum acpi_backlight_type acpi_video_get_backlight_type(void);

extern void acpi_video_set_dmi_backlight_type(enum acpi_backlight_type type);

#else

static inline int acpi_video_register(void) { return 0; }

static inline void acpi_video_unregister(void) { return; }
@@ -33,6 +43,13 @@ static inline int acpi_video_get_edid(struct acpi_device *device, int type, 
	return -ENODEV;

}

static inline bool acpi_video_verify_backlight_support(void) { return false; }

static inline enum acpi_backlight_type acpi_video_get_backlight_type(void)

{

	return acpi_backlight_vendor;

}

static void acpi_video_set_dmi_backlight_type(enum acpi_backlight_type type)

{

}

#endif



#endif