ACPI video: if no ACPI backlight support, use vendor drivers

If an ACPI graphics device supports backlight brightness functions (cmp. with
latest ACPI spec Appendix B), let the ACPI video driver control backlight and
switch backlight control off in vendor specific ACPI drivers (asus_acpi,
thinkpad_acpi, eeepc, fujitsu_laptop, msi_laptop, sony_laptop, acer-wmi).

Currently it is possible to load above drivers and let both poke on the
brightness HW registers, the video and vendor specific ACPI drivers -> bad.

This patch provides the basic support to check for BIOS capabilities before
driver loading time. Driver specific modifications are in separate follow up
patches.

"acpi_backlight=vendor"
	Prever vendor driver over ACPI driver for backlight.
"acpi_backlight=video" (default)
	Prever ACPI driver over vendor driver for backlight.
Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

Documentation/kernel-parameters.txt

@@ -198,6 +198,18 @@ and is between 256 and 4096 characters. It is defined in the file
 			that require a timer override, but don't have
 			HPET
 
+	acpi_backlight=	[HW,ACPI]
+			acpi_backlight=vendor
+			acpi_backlight=video
+			If set to vendor, prefer vendor specific driver
+			(e.g. thinkpad_acpi, sony_acpi, etc.) instead
+			of the ACPI video.ko driver.
+
+	acpi_display_output=	[HW,ACPI]
+			acpi_display_output=vendor
+			acpi_display_output=video
+			See above.
+
 	acpi.debug_layer=	[HW,ACPI]
 			Format: <int>
 			Each bit of the <int> indicates an ACPI debug layer,

drivers/acpi/Makefile

@@ -46,6 +46,10 @@ obj-$(CONFIG_ACPI_BUTTON)	+= button.o
 obj-$(CONFIG_ACPI_FAN)		+= fan.o
 obj-$(CONFIG_ACPI_DOCK)		+= dock.o
 obj-$(CONFIG_ACPI_VIDEO)	+= video.o
+ifdef CONFIG_ACPI_VIDEO
+obj-y				+= video_detect.o
+endif
+
 obj-y				+= pci_root.o pci_link.o pci_irq.o pci_bind.o
 obj-$(CONFIG_ACPI_PCI_SLOT)	+= pci_slot.o
 obj-$(CONFIG_ACPI_PROCESSOR)	+= processor.o

drivers/acpi/scan.c

@@ -919,36 +919,6 @@ static void acpi_device_get_busid(struct acpi_device *device,
 	}
 }
 
-static int
-acpi_video_bus_match(struct acpi_device *device)
-{
-	acpi_handle h_dummy;
-
-	if (!device)
-		return -EINVAL;
-
-	/* Since there is no HID, CID for ACPI Video drivers, we have
-	 * to check well known required nodes for each feature we support.
-	 */
-
-	/* Does this device able to support video switching ? */
-	if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOD", &h_dummy)) &&
-	    ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOS", &h_dummy)))
-		return 0;
-
-	/* Does this device able to retrieve a video ROM ? */
-	if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_ROM", &h_dummy)))
-		return 0;
-
-	/* Does this device able to configure which video head to be POSTed ? */
-	if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_VPO", &h_dummy)) &&
-	    ACPI_SUCCESS(acpi_get_handle(device->handle, "_GPD", &h_dummy)) &&
-	    ACPI_SUCCESS(acpi_get_handle(device->handle, "_SPD", &h_dummy)))
-		return 0;
-
-	return -ENODEV;
-}
-
 /*
  * acpi_bay_match - see if a device is an ejectable driver bay
  *
@@ -1031,7 +1001,7 @@ static void acpi_device_set_id(struct acpi_device *device,
 		   will get autoloaded and the device might still match
 		   against another driver.
 		*/
-		if (ACPI_SUCCESS(acpi_video_bus_match(device)))
+		if (acpi_is_video_device(device))
 			cid_add = ACPI_VIDEO_HID;
 		else if (ACPI_SUCCESS(acpi_bay_match(device)))
 			cid_add = ACPI_BAY_HID;

drivers/acpi/video.c

@@ -739,7 +739,8 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
 		device->cap._DSS = 1;
 	}
 
-	max_level = acpi_video_init_brightness(device);
+	if (acpi_video_backlight_support())
+		max_level = acpi_video_init_brightness(device);
 
 	if (device->cap._BCL && device->cap._BCM && max_level > 0) {
 		int result;
@@ -785,18 +786,21 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
 			printk(KERN_ERR PREFIX "Create sysfs link\n");
 
 	}
-	if (device->cap._DCS && device->cap._DSS){
-		static int count = 0;
-		char *name;
-		name = kzalloc(MAX_NAME_LEN, GFP_KERNEL);
-		if (!name)
-			return;
-		sprintf(name, "acpi_video%d", count++);
-		device->output_dev = video_output_register(name,
-				NULL, device, &acpi_output_properties);
-		kfree(name);
+
+	if (acpi_video_display_switch_support()) {
+
+		if (device->cap._DCS && device->cap._DSS) {
+			static int count;
+			char *name;
+			name = kzalloc(MAX_NAME_LEN, GFP_KERNEL);
+			if (!name)
+				return;
+			sprintf(name, "acpi_video%d", count++);
+			device->output_dev = video_output_register(name,
+					NULL, device, &acpi_output_properties);
+			kfree(name);
+		}
 	}
-	return;
 }
 
 /*

drivers/acpi/video_detect.c

+/*
+ *  Copyright (C) 2008       SuSE Linux Products GmbH
+ *                           Thomas Renninger <trenn@suse.de>
+ *
+ *  May be copied or modified under the terms of the GNU General Public License
+ *
+ * video_detect.c:
+ * Provides acpi_is_video_device() for early scanning of ACPI devices in scan.c
+ * There a Linux specific (Spec does not provide a HID for video devices) is
+ * assinged
+ *
+ * After PCI devices are glued with ACPI devices
+ * acpi_get_physical_pci_device() 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 (or display output) 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_acpi,
+ * sony_acpi,... can take care about backlight brightness and display output
+ * switching.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/acpi.h>
+#include <linux/dmi.h>
+
+ACPI_MODULE_NAME("video");
+#define ACPI_VIDEO_COMPONENT		0x08000000
+#define _COMPONENT		ACPI_VIDEO_COMPONENT
+
+static long acpi_video_support;
+static bool acpi_video_caps_checked;
+
+static acpi_status
+acpi_backlight_cap_match(acpi_handle handle, u32 level, void *context,
+			  void **retyurn_value)
+{
+	long *cap = context;
+	acpi_handle h_dummy;
+
+	if (ACPI_SUCCESS(acpi_get_handle(handle, "_BCM", &h_dummy)) &&
+	    ACPI_SUCCESS(acpi_get_handle(handle, "_BCL", &h_dummy))) {
+		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found generic backlight "
+				  "support\n"));
+		*cap |= ACPI_VIDEO_BACKLIGHT;
+		/* We have backlight support, no need to scan further */
+		return AE_CTRL_TERMINATE;
+	}
+	return 0;
+}
+
+/* Returns true if the device is a video device which can be handled by
+ * video.ko.
+ * The device will get a Linux specific CID added in scan.c to
+ * identify the device as an ACPI graphics device
+ * Be aware that the graphics device may not be physically present
+ * Use acpi_video_get_capabilities() to detect general ACPI video
+ * capabilities of present cards
+ */
+long acpi_is_video_device(struct acpi_device *device)
+{
+	acpi_handle h_dummy;
+	long video_caps = 0;
+
+	if (!device)
+		return 0;
+
+	/* Does this device able to support video switching ? */
+	if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOD", &h_dummy)) &&
+	    ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOS", &h_dummy)))
+		video_caps |= ACPI_VIDEO_OUTPUT_SWITCHING;
+
+	/* Does this device able to retrieve a video ROM ? */
+	if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_ROM", &h_dummy)))
+		video_caps |= ACPI_VIDEO_ROM_AVAILABLE;
+
+	/* Does this device able to configure which video head to be POSTed ? */
+	if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_VPO", &h_dummy)) &&
+	    ACPI_SUCCESS(acpi_get_handle(device->handle, "_GPD", &h_dummy)) &&
+	    ACPI_SUCCESS(acpi_get_handle(device->handle, "_SPD", &h_dummy)))
+		video_caps |= ACPI_VIDEO_DEVICE_POSTING;
+
+	/* Only check for backlight functionality if one of the above hit. */
+	if (video_caps)
+		acpi_walk_namespace(ACPI_TYPE_DEVICE, device->handle,
+				    ACPI_UINT32_MAX, acpi_backlight_cap_match,
+				    &video_caps, NULL);
+
+	return video_caps;
+}
+EXPORT_SYMBOL(acpi_is_video_device);
+
+static acpi_status
+find_video(acpi_handle handle, u32 lvl, void *context, void **rv)
+{
+	long *cap = context;
+	struct device *dev;
+	struct acpi_device *acpi_dev;
+
+	const struct acpi_device_id video_ids[] = {
+		{ACPI_VIDEO_HID, 0},
+		{"", 0},
+	};
+	if (acpi_bus_get_device(handle, &acpi_dev))
+		return AE_OK;
+
+	if (!acpi_match_device_ids(acpi_dev, video_ids)) {
+		dev = acpi_get_physical_pci_device(handle);
+		if (!dev)
+			return AE_OK;
+		put_device(dev);
+		*cap |= acpi_is_video_device(acpi_dev);
+	}
+	return AE_OK;
+}
+
+/*
+ * Returns the video capabilities of a specific ACPI graphics device
+ *
+ * if NULL is passed as argument all ACPI devices are enumerated and
+ * all graphics capabilities of physically present devices are
+ * summerized and returned. This is cached and done only once.
+ */
+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,
+				    &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.:
+		 *
+		 *   if (dmi_name_in_vendors("XY")) {
+		 *	acpi_video_support |=
+		 *		ACPI_VIDEO_OUTPUT_SWITCHING_DMI_VENDOR;
+		 *	acpi_video_support |=
+		 *		ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
+		 *}
+		 */
+	} 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_UINT32_MAX, find_video,
+				    &caps, NULL);
+	}
+	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;
+}
+EXPORT_SYMBOL(acpi_video_get_capabilities);
+
+/* Returns true if video.ko can do backlight switching */
+int acpi_video_backlight_support(void)
+{
+	/*
+	 * We must check whether the ACPI graphics device is physically plugged
+	 * in. Therefore this must be called after binding PCI and ACPI devices
+	 */
+	if (!acpi_video_caps_checked)
+		acpi_video_get_capabilities(NULL);
+
+	/* 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;
+}
+EXPORT_SYMBOL(acpi_video_backlight_support);
+
+/*
+ * Returns true if video.ko can do display output switching.
+ * This does not work well/at all with binary graphics drivers
+ * which disable system io ranges and do it on their own.
+ */
+int acpi_video_display_switch_support(void)
+{
+	if (!acpi_video_caps_checked)
+		acpi_video_get_capabilities(NULL);
+
+	if (acpi_video_support & ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VENDOR)
+		return 0;
+	else if (acpi_video_support & ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VIDEO)
+		return 1;
+
+	if (acpi_video_support & ACPI_VIDEO_OUTPUT_SWITCHING_DMI_VENDOR)
+		return 0;
+	else if (acpi_video_support & ACPI_VIDEO_OUTPUT_SWITCHING_DMI_VIDEO)
+		return 1;
+
+	return acpi_video_support & ACPI_VIDEO_OUTPUT_SWITCHING;
+}
+EXPORT_SYMBOL(acpi_video_display_switch_support);
+
+/*
+ * Use acpi_display_output=vendor/video or acpi_backlight=vendor/video
+ * To force that backlight or display output switching is processed by vendor
+ * specific acpi drivers or video.ko driver.
+ */
+int __init acpi_backlight(char *str)
+{
+	if (str == NULL || *str == '\0')
+		return 1;
+	else {
+		if (!strcmp("vendor", str))
+			acpi_video_support |=
+				ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR;
+		if (!strcmp("video", str))
+			acpi_video_support |=
+				ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VIDEO;
+	}
+	return 1;
+}
+__setup("acpi_backlight=", acpi_backlight);
+
+int __init acpi_display_output(char *str)
+{
+	if (str == NULL || *str == '\0')
+		return 1;
+	else {
+		if (!strcmp("vendor", str))
+			acpi_video_support |=
+				ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VENDOR;
+		if (!strcmp("video", str))
+			acpi_video_support |=
+				ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VIDEO;
+	}
+	return 1;
+}
+__setup("acpi_display_output=", acpi_display_output);

include/linux/acpi.h

@@ -194,6 +194,50 @@ extern bool wmi_has_guid(const char *guid);
 
 #endif	/* CONFIG_ACPI_WMI */
 
+#define ACPI_VIDEO_OUTPUT_SWITCHING			0x0001
+#define ACPI_VIDEO_DEVICE_POSTING			0x0002
+#define ACPI_VIDEO_ROM_AVAILABLE			0x0004
+#define ACPI_VIDEO_BACKLIGHT				0x0008
+#define ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR		0x0010
+#define ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO		0x0020
+#define ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VENDOR	0x0040
+#define ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VIDEO		0x0080
+#define ACPI_VIDEO_BACKLIGHT_DMI_VENDOR			0x0100
+#define ACPI_VIDEO_BACKLIGHT_DMI_VIDEO			0x0200
+#define ACPI_VIDEO_OUTPUT_SWITCHING_DMI_VENDOR		0x0400
+#define ACPI_VIDEO_OUTPUT_SWITCHING_DMI_VIDEO		0x0800
+
+#if defined(CONFIG_ACPI_VIDEO) || defined(CONFIG_ACPI_VIDEO_MODULE)
+
+extern long acpi_video_get_capabilities(acpi_handle graphics_dev_handle);
+extern long acpi_is_video_device(struct acpi_device *device);
+extern int acpi_video_backlight_support(void);
+extern int acpi_video_display_switch_support(void);
+
+#else
+
+static inline long acpi_video_get_capabilities(acpi_handle graphics_dev_handle)
+{
+	return 0;
+}
+
+static inline long acpi_is_video_device(struct acpi_device *device)
+{
+	return 0;
+}
+
+static inline int acpi_video_backlight_support(void)
+{
+	return 0;
+}
+
+static inline int acpi_video_display_switch_support(void)
+{
+	return 0;
+}
+
+#endif /* defined(CONFIG_ACPI_VIDEO) || defined(CONFIG_ACPI_VIDEO_MODULE) */
+
 extern int acpi_blacklisted(void);
 #ifdef CONFIG_DMI
 extern void acpi_dmi_osi_linux(int enable, const struct dmi_system_id *d);