diff --git a/Documentation/firmware-guide/acpi/namespace.rst b/Documentation/firmware-guide/acpi/namespace.rst
index 835521baeb89..3eb763d6656d 100644
--- a/Documentation/firmware-guide/acpi/namespace.rst
+++ b/Documentation/firmware-guide/acpi/namespace.rst
@@ -261,7 +261,7 @@ Description Tables contain information used for the creation of the
 struct acpi_device objects represented by the given row (xSDT means DSDT
 or SSDT).
 
-The forth column of the above table indicates the 'bus_id' generation
+The fourth column of the above table indicates the 'bus_id' generation
 rule of the struct acpi_device object:
 
    _HID:
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 68853f23e901..61d31c36ed8a 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -48,7 +48,7 @@ acpi-y				+= acpi_pnp.o
 acpi-$(CONFIG_ARM_AMBA)	+= acpi_amba.o
 acpi-y				+= power.o
 acpi-y				+= event.o
-acpi-$(CONFIG_ACPI_REDUCED_HARDWARE_ONLY) += evged.o
+acpi-y				+= evged.o
 acpi-y				+= sysfs.o
 acpi-y				+= property.o
 acpi-$(CONFIG_X86)		+= acpi_cmos_rtc.o
diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
index 751ed38f2a10..70f740b09684 100644
--- a/drivers/acpi/acpi_lpss.c
+++ b/drivers/acpi/acpi_lpss.c
@@ -499,31 +499,16 @@ static const struct lpss_device_links lpss_device_links[] = {
 	{"80860F41", "7", "LNXVIDEO", NULL, DL_FLAG_PM_RUNTIME},
 };
 
-static bool hid_uid_match(struct acpi_device *adev,
-			  const char *hid2, const char *uid2)
-{
-	const char *hid1 = acpi_device_hid(adev);
-	const char *uid1 = acpi_device_uid(adev);
-
-	if (strcmp(hid1, hid2))
-		return false;
-
-	if (!uid2)
-		return true;
-
-	return uid1 && !strcmp(uid1, uid2);
-}
-
 static bool acpi_lpss_is_supplier(struct acpi_device *adev,
 				  const struct lpss_device_links *link)
 {
-	return hid_uid_match(adev, link->supplier_hid, link->supplier_uid);
+	return acpi_dev_hid_uid_match(adev, link->supplier_hid, link->supplier_uid);
 }
 
 static bool acpi_lpss_is_consumer(struct acpi_device *adev,
 				  const struct lpss_device_links *link)
 {
-	return hid_uid_match(adev, link->consumer_hid, link->consumer_uid);
+	return acpi_dev_hid_uid_match(adev, link->consumer_hid, link->consumer_uid);
 }
 
 struct hid_uid {
@@ -539,7 +524,7 @@ static int match_hid_uid(struct device *dev, const void *data)
 	if (!adev)
 		return 0;
 
-	return hid_uid_match(adev, id->hid, id->uid);
+	return acpi_dev_hid_uid_match(adev, id->hid, id->uid);
 }
 
 static struct device *acpi_lpss_find_device(const char *hid, const char *uid)
diff --git a/drivers/acpi/acpi_platform.c b/drivers/acpi/acpi_platform.c
index 00ec4f2bf015..c05050f474cd 100644
--- a/drivers/acpi/acpi_platform.c
+++ b/drivers/acpi/acpi_platform.c
@@ -31,6 +31,44 @@ static const struct acpi_device_id forbidden_id_list[] = {
 	{"", 0},
 };
 
+static struct platform_device *acpi_platform_device_find_by_companion(struct acpi_device *adev)
+{
+	struct device *dev;
+
+	dev = bus_find_device_by_acpi_dev(&platform_bus_type, adev);
+	return dev ? to_platform_device(dev) : NULL;
+}
+
+static int acpi_platform_device_remove_notify(struct notifier_block *nb,
+					      unsigned long value, void *arg)
+{
+	struct acpi_device *adev = arg;
+	struct platform_device *pdev;
+
+	switch (value) {
+	case ACPI_RECONFIG_DEVICE_ADD:
+		/* Nothing to do here */
+		break;
+	case ACPI_RECONFIG_DEVICE_REMOVE:
+		if (!acpi_device_enumerated(adev))
+			break;
+
+		pdev = acpi_platform_device_find_by_companion(adev);
+		if (!pdev)
+			break;
+
+		platform_device_unregister(pdev);
+		put_device(&pdev->dev);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block acpi_platform_notifier = {
+	.notifier_call = acpi_platform_device_remove_notify,
+};
+
 static void acpi_platform_fill_resource(struct acpi_device *adev,
 	const struct resource *src, struct resource *dest)
 {
@@ -130,3 +168,8 @@ struct platform_device *acpi_create_platform_device(struct acpi_device *adev,
 	return pdev;
 }
 EXPORT_SYMBOL_GPL(acpi_create_platform_device);
+
+void __init acpi_platform_init(void)
+{
+	acpi_reconfig_notifier_register(&acpi_platform_notifier);
+}
diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
index 4f325e47519f..2f380e7381d6 100644
--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -699,9 +699,13 @@ acpi_video_device_EDID(struct acpi_video_device *device,
  *			event notify code.
  *	lcd_flag	:
  *		0.	The system BIOS should automatically control the brightness level
- *			of the LCD when the power changes from AC to DC
+ *			of the LCD when:
+ *			- the power changes from AC to DC (ACPI appendix B)
+ *			- a brightness hotkey gets pressed (implied by Win7/8 backlight docs)
  *		1.	The system BIOS should NOT automatically control the brightness
- *			level of the LCD when the power changes from AC to DC.
+ *			level of the LCD when:
+ *			- the power changes from AC to DC (ACPI appendix B)
+ *			- a brightness hotkey gets pressed (implied by Win7/8 backlight docs)
  *  Return Value:
  *		-EINVAL	wrong arg.
  */
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index aad6be5c0af0..915650bf519f 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2174,6 +2174,7 @@ int __init acpi_scan_init(void)
 	acpi_pci_root_init();
 	acpi_pci_link_init();
 	acpi_processor_init();
+	acpi_platform_init();
 	acpi_lpss_init();
 	acpi_apd_init();
 	acpi_cmos_rtc_init();
diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index e3974a8f8fd4..804ac0df58ec 100644
--- a/drivers/acpi/utils.c
+++ b/drivers/acpi/utils.c
@@ -455,6 +455,7 @@ EXPORT_SYMBOL(acpi_evaluate_ost);
 
 /**
  * acpi_handle_path: Return the object path of handle
+ * @handle: ACPI device handle
  *
  * Caller must free the returned buffer
  */
@@ -473,6 +474,9 @@ static char *acpi_handle_path(acpi_handle handle)
 
 /**
  * acpi_handle_printk: Print message with ACPI prefix and object path
+ * @level: log level
+ * @handle: ACPI device handle
+ * @fmt: format string
  *
  * This function is called through acpi_handle_<level> macros and prints
  * a message with ACPI prefix and object path.  This function acquires
@@ -501,6 +505,9 @@ EXPORT_SYMBOL(acpi_handle_printk);
 #if defined(CONFIG_DYNAMIC_DEBUG)
 /**
  * __acpi_handle_debug: pr_debug with ACPI prefix and object path
+ * @descriptor: Dynamic Debug descriptor
+ * @handle: ACPI device handle
+ * @fmt: format string
  *
  * This function is called through acpi_handle_debug macro and debug
  * prints a message with ACPI prefix and object path. This function
@@ -694,6 +701,31 @@ bool acpi_check_dsm(acpi_handle handle, const guid_t *guid, u64 rev, u64 funcs)
 }
 EXPORT_SYMBOL(acpi_check_dsm);
 
+/**
+ * acpi_dev_hid_uid_match - Match device by supplied HID and UID
+ * @adev: ACPI device to match.
+ * @hid2: Hardware ID of the device.
+ * @uid2: Unique ID of the device, pass NULL to not check _UID.
+ *
+ * Matches HID and UID in @adev with given @hid2 and @uid2.
+ * Returns true if matches.
+ */
+bool acpi_dev_hid_uid_match(struct acpi_device *adev,
+			    const char *hid2, const char *uid2)
+{
+	const char *hid1 = acpi_device_hid(adev);
+	const char *uid1 = acpi_device_uid(adev);
+
+	if (strcmp(hid1, hid2))
+		return false;
+
+	if (!uid2)
+		return true;
+
+	return uid1 && !strcmp(uid1, uid2);
+}
+EXPORT_SYMBOL(acpi_dev_hid_uid_match);
+
 /**
  * acpi_dev_found - Detect presence of a given ACPI device in the namespace.
  * @hid: Hardware ID of the device.
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index dd555078258c..12e5039a7a25 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -124,30 +124,6 @@ static struct lock_class_key reserved_rbtree_key;
  *
  ****************************************************************************/
 
-static inline int match_hid_uid(struct device *dev,
-				struct acpihid_map_entry *entry)
-{
-	struct acpi_device *adev = ACPI_COMPANION(dev);
-	const char *hid, *uid;
-
-	if (!adev)
-		return -ENODEV;
-
-	hid = acpi_device_hid(adev);
-	uid = acpi_device_uid(adev);
-
-	if (!hid || !(*hid))
-		return -ENODEV;
-
-	if (!uid || !(*uid))
-		return strcmp(hid, entry->hid);
-
-	if (!(*entry->uid))
-		return strcmp(hid, entry->hid);
-
-	return (strcmp(hid, entry->hid) || strcmp(uid, entry->uid));
-}
-
 static inline u16 get_pci_device_id(struct device *dev)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
@@ -158,10 +134,14 @@ static inline u16 get_pci_device_id(struct device *dev)
 static inline int get_acpihid_device_id(struct device *dev,
 					struct acpihid_map_entry **entry)
 {
+	struct acpi_device *adev = ACPI_COMPANION(dev);
 	struct acpihid_map_entry *p;
 
+	if (!adev)
+		return -ENODEV;
+
 	list_for_each_entry(p, &acpihid_map, list) {
-		if (!match_hid_uid(dev, p)) {
+		if (acpi_dev_hid_uid_match(adev, p->hid, p->uid)) {
 			if (entry)
 				*entry = p;
 			return p->devid;
diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c
index 1604f512c7bd..105e73d4a3b9 100644
--- a/drivers/mmc/host/sdhci-acpi.c
+++ b/drivers/mmc/host/sdhci-acpi.c
@@ -61,7 +61,7 @@ struct sdhci_acpi_slot {
 	mmc_pm_flag_t	pm_caps;
 	unsigned int	flags;
 	size_t		priv_size;
-	int (*probe_slot)(struct platform_device *, const char *, const char *);
+	int (*probe_slot)(struct platform_device *, struct acpi_device *);
 	int (*remove_slot)(struct platform_device *);
 	int (*free_slot)(struct platform_device *pdev);
 	int (*setup_host)(struct platform_device *pdev);
@@ -325,12 +325,10 @@ static bool sdhci_acpi_cht_pci_wifi(unsigned int vendor, unsigned int device,
  * wifi card in the expected slot with an ACPI companion node, is used to
  * indicate that acpi_device_fix_up_power() should be avoided.
  */
-static inline bool sdhci_acpi_no_fixup_child_power(const char *hid,
-						   const char *uid)
+static inline bool sdhci_acpi_no_fixup_child_power(struct acpi_device *adev)
 {
 	return sdhci_acpi_cht() &&
-	       !strcmp(hid, "80860F14") &&
-	       !strcmp(uid, "2") &&
+	       acpi_dev_hid_uid_match(adev, "80860F14", "2") &&
 	       sdhci_acpi_cht_pci_wifi(0x14e4, 0x43ec, 0, 28);
 }
 
@@ -345,8 +343,7 @@ static inline bool sdhci_acpi_byt_defer(struct device *dev)
 	return false;
 }
 
-static inline bool sdhci_acpi_no_fixup_child_power(const char *hid,
-						   const char *uid)
+static inline bool sdhci_acpi_no_fixup_child_power(struct acpi_device *adev)
 {
 	return false;
 }
@@ -375,19 +372,18 @@ out:
 	return ret;
 }
 
-static int intel_probe_slot(struct platform_device *pdev, const char *hid,
-			    const char *uid)
+static int intel_probe_slot(struct platform_device *pdev, struct acpi_device *adev)
 {
 	struct sdhci_acpi_host *c = platform_get_drvdata(pdev);
 	struct intel_host *intel_host = sdhci_acpi_priv(c);
 	struct sdhci_host *host = c->host;
 
-	if (hid && uid && !strcmp(hid, "80860F14") && !strcmp(uid, "1") &&
+	if (acpi_dev_hid_uid_match(adev, "80860F14", "1") &&
 	    sdhci_readl(host, SDHCI_CAPABILITIES) == 0x446cc8b2 &&
 	    sdhci_readl(host, SDHCI_CAPABILITIES_1) == 0x00000807)
 		host->timeout_clk = 1000; /* 1000 kHz i.e. 1 MHz */
 
-	if (hid && !strcmp(hid, "80865ACA"))
+	if (acpi_dev_hid_uid_match(adev, "80865ACA", NULL))
 		host->mmc_host_ops.get_cd = bxt_get_cd;
 
 	intel_dsm_init(intel_host, &pdev->dev, host->mmc);
@@ -473,8 +469,7 @@ static irqreturn_t sdhci_acpi_qcom_handler(int irq, void *ptr)
 	return IRQ_HANDLED;
 }
 
-static int qcom_probe_slot(struct platform_device *pdev, const char *hid,
-			   const char *uid)
+static int qcom_probe_slot(struct platform_device *pdev, struct acpi_device *adev)
 {
 	struct sdhci_acpi_host *c = platform_get_drvdata(pdev);
 	struct sdhci_host *host = c->host;
@@ -482,7 +477,7 @@ static int qcom_probe_slot(struct platform_device *pdev, const char *hid,
 
 	*irq = -EINVAL;
 
-	if (strcmp(hid, "QCOM8051"))
+	if (!acpi_dev_hid_uid_match(adev, "QCOM8051", NULL))
 		return 0;
 
 	*irq = platform_get_irq(pdev, 1);
@@ -501,14 +496,12 @@ static int qcom_free_slot(struct platform_device *pdev)
 	struct sdhci_host *host = c->host;
 	struct acpi_device *adev;
 	int *irq = sdhci_acpi_priv(c);
-	const char *hid;
 
 	adev = ACPI_COMPANION(dev);
 	if (!adev)
 		return -ENODEV;
 
-	hid = acpi_device_hid(adev);
-	if (strcmp(hid, "QCOM8051"))
+	if (!acpi_dev_hid_uid_match(adev, "QCOM8051", NULL))
 		return 0;
 
 	if (*irq < 0)
@@ -583,7 +576,7 @@ static const struct sdhci_acpi_chip sdhci_acpi_chip_amd = {
 };
 
 static int sdhci_acpi_emmc_amd_probe_slot(struct platform_device *pdev,
-					  const char *hid, const char *uid)
+					  struct acpi_device *adev)
 {
 	struct sdhci_acpi_host *c = platform_get_drvdata(pdev);
 	struct sdhci_host *host   = c->host;
@@ -654,17 +647,12 @@ static const struct acpi_device_id sdhci_acpi_ids[] = {
 };
 MODULE_DEVICE_TABLE(acpi, sdhci_acpi_ids);
 
-static const struct sdhci_acpi_slot *sdhci_acpi_get_slot(const char *hid,
-							 const char *uid)
+static const struct sdhci_acpi_slot *sdhci_acpi_get_slot(struct acpi_device *adev)
 {
 	const struct sdhci_acpi_uid_slot *u;
 
 	for (u = sdhci_acpi_uids; u->hid; u++) {
-		if (strcmp(u->hid, hid))
-			continue;
-		if (!u->uid)
-			return u->slot;
-		if (uid && !strcmp(u->uid, uid))
+		if (acpi_dev_hid_uid_match(adev, u->hid, u->uid))
 			return u->slot;
 	}
 	return NULL;
@@ -680,22 +668,17 @@ static int sdhci_acpi_probe(struct platform_device *pdev)
 	struct resource *iomem;
 	resource_size_t len;
 	size_t priv_size;
-	const char *hid;
-	const char *uid;
 	int err;
 
 	device = ACPI_COMPANION(dev);
 	if (!device)
 		return -ENODEV;
 
-	hid = acpi_device_hid(device);
-	uid = acpi_device_uid(device);
-
-	slot = sdhci_acpi_get_slot(hid, uid);
+	slot = sdhci_acpi_get_slot(device);
 
 	/* Power on the SDHCI controller and its children */
 	acpi_device_fix_up_power(device);
-	if (!sdhci_acpi_no_fixup_child_power(hid, uid)) {
+	if (!sdhci_acpi_no_fixup_child_power(device)) {
 		list_for_each_entry(child, &device->children, node)
 			if (child->status.present && child->status.enabled)
 				acpi_device_fix_up_power(child);
@@ -745,7 +728,7 @@ static int sdhci_acpi_probe(struct platform_device *pdev)
 
 	if (c->slot) {
 		if (c->slot->probe_slot) {
-			err = c->slot->probe_slot(pdev, hid, uid);
+			err = c->slot->probe_slot(pdev, device);
 			if (err)
 				goto err_free;
 		}
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 175f7b40c585..0c23fd0548d1 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -78,9 +78,6 @@ acpi_evaluate_dsm_typed(acpi_handle handle, const guid_t *guid, u64 rev,
 bool acpi_dev_found(const char *hid);
 bool acpi_dev_present(const char *hid, const char *uid, s64 hrv);
 
-struct acpi_device *
-acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv);
-
 #ifdef CONFIG_ACPI
 
 #include <linux/proc_fs.h>
@@ -683,6 +680,11 @@ static inline bool acpi_device_can_poweroff(struct acpi_device *adev)
 		adev->power.states[ACPI_STATE_D3_HOT].flags.explicit_set);
 }
 
+bool acpi_dev_hid_uid_match(struct acpi_device *adev, const char *hid2, const char *uid2);
+
+struct acpi_device *
+acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv);
+
 static inline void acpi_dev_put(struct acpi_device *adev)
 {
 	put_device(&adev->dev);
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 8b4e516bac00..0f37a7d5fa77 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -678,6 +678,14 @@ static inline bool acpi_dev_present(const char *hid, const char *uid, s64 hrv)
 	return false;
 }
 
+struct acpi_device;
+
+static inline bool
+acpi_dev_hid_uid_match(struct acpi_device *adev, const char *hid2, const char *uid2)
+{
+	return false;
+}
+
 static inline struct acpi_device *
 acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv)
 {