diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index f6e98dd..fdc833d 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -35,6 +35,8 @@ i915-y := i915_drv.o i915_dma.o i915_irq.o i915_mem.o \
 
 i915-$(CONFIG_COMPAT)   += i915_ioc32.o
 
+i915-$(CONFIG_ACPI)	+= intel_acpi.o
+
 obj-$(CONFIG_DRM_I915)  += i915.o
 
 CFLAGS_i915_trace_points.o := -I$(src)
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 726c373..778c01c 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1244,6 +1244,8 @@ static int i915_load_modeset_init(struct drm_device *dev,
 	if (ret)
 		goto cleanup_ringbuffer;
 
+	intel_register_dsm_handler();
+
 	ret = vga_switcheroo_register_client(dev->pdev,
 					     i915_switcheroo_set_state,
 					     i915_switcheroo_can_switch);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 73ad8bf..e4ffcd3 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1136,6 +1136,15 @@ static inline void intel_opregion_gse_intr(struct drm_device *dev) { return; }
 static inline void intel_opregion_enable_asle(struct drm_device *dev) { return; }
 #endif
 
+/* intel_acpi.c */
+#ifdef CONFIG_ACPI
+extern void intel_register_dsm_handler(void);
+extern void intel_unregister_dsm_handler(void);
+#else
+static inline void intel_register_dsm_handler(void) { return; }
+static inline void intel_unregister_dsm_handler(void) { return; }
+#endif /* CONFIG_ACPI */
+
 /* modesetting */
 extern void intel_modeset_init(struct drm_device *dev);
 extern void intel_modeset_cleanup(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/intel_acpi.c b/drivers/gpu/drm/i915/intel_acpi.c
new file mode 100644
index 0000000..c68d496
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_acpi.c
@@ -0,0 +1,290 @@
+/*
+ * Intel ACPI functions
+ *
+ * _DSM related code stolen from nouveau_acpi.c.
+ */
+#include <linux/pci.h>
+#include <linux/acpi.h>
+#include <linux/vga_switcheroo.h>
+#include <acpi/acpi_drivers.h>
+
+#include "drmP.h"
+
+#define INTEL_DSM_REVISION_ID 1 /* For Calpella anyway... */
+
+#define INTEL_DSM_FN_SUPPORTED_FUNCTIONS 0 /* No args */
+#define INTEL_DSM_FN_PLATFORM_MUX_INFO 1 /* No args */
+
+static struct intel_dsm_priv {
+	bool dsm_detected;
+	acpi_handle dhandle;
+} intel_dsm_priv;
+
+static const u8 intel_dsm_guid[] = {
+	0xd3, 0x73, 0xd8, 0x7e,
+	0xd0, 0xc2,
+	0x4f, 0x4e,
+	0xa8, 0x54,
+	0x0f, 0x13, 0x17, 0xb0, 0x1c, 0x2c
+};
+
+static int intel_dsm(acpi_handle handle, int func, int arg, u32 *result)
+{
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct acpi_object_list input;
+	union acpi_object params[4];
+	union acpi_object *obj;
+	int ret = 0;
+
+	input.count = 4;
+	input.pointer = params;
+	params[0].type = ACPI_TYPE_BUFFER;
+	params[0].buffer.length = sizeof(intel_dsm_guid);
+	params[0].buffer.pointer = (char *)intel_dsm_guid;
+	params[1].type = ACPI_TYPE_INTEGER;
+	params[1].integer.value = INTEL_DSM_REVISION_ID;
+	params[2].type = ACPI_TYPE_INTEGER;
+	params[2].integer.value = func;
+	params[3].type = ACPI_TYPE_INTEGER;
+	params[3].integer.value = arg;
+
+	ret = acpi_evaluate_object(handle, "_DSM", &input, &output);
+	if (ret) {
+		DRM_DEBUG_DRIVER("failed to evaluate _DSM: %d\n", ret);
+		goto out;
+	}
+
+	obj = (union acpi_object *)output.pointer;
+
+	if (obj->type == ACPI_TYPE_INTEGER)
+		if (obj->integer.value == 0x80000002) {
+			ret = -ENODEV;
+			goto out;
+		}
+
+	if (obj->type == ACPI_TYPE_BUFFER) {
+		if (obj->buffer.length == 4 && result) {
+			*result = 0;
+			*result |= obj->buffer.pointer[0];
+			*result |= (obj->buffer.pointer[1] << 8);
+			*result |= (obj->buffer.pointer[2] << 16);
+			*result |= (obj->buffer.pointer[3] << 24);
+		}
+	}
+
+	if (*result == 0x80000002)
+		ret = -ENODEV;
+
+out:
+	kfree(output.pointer);
+	return ret;
+}
+
+static char *intel_dsm_port_name(u8 id)
+{
+	switch (id) {
+	case 0:
+		return "Reserved";
+	case 1:
+		return "Analog VGA";
+	case 2:
+		return "LVDS";
+	case 3:
+		return "Reserved";
+	case 4:
+		return "HDMI/DVI_B";
+	case 5:
+		return "HDMI/DVI_C";
+	case 6:
+		return "HDMI/DVI_D";
+	case 7:
+		return "DisplayPort_A";
+	case 8:
+		return "DisplayPort_B";
+	case 9:
+		return "DisplayPort_C";
+	case 0xa:
+		return "DisplayPort_D";
+	case 0xb:
+	case 0xc:
+	case 0xd:
+		return "Reserved";
+	case 0xe:
+		return "WiDi";
+	default:
+		return "bad type";
+	}
+}
+
+static char *intel_dsm_mux_type(u8 type)
+{
+	switch (type) {
+	case 0:
+		return "unknown";
+	case 1:
+		return "No MUX, iGPU only";
+	case 2:
+		return "No MUX, dGPU only";
+	case 3:
+		return "MUXed between iGPU and dGPU";
+	default:
+		return "bad type";
+	}
+}
+
+static void intel_dsm_platform_mux_info(void)
+{
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct acpi_object_list input;
+	union acpi_object params[4];
+	union acpi_object *pkg;
+	int i, ret;
+
+	input.count = 4;
+	input.pointer = params;
+	params[0].type = ACPI_TYPE_BUFFER;
+	params[0].buffer.length = sizeof(intel_dsm_guid);
+	params[0].buffer.pointer = (char *)intel_dsm_guid;
+	params[1].type = ACPI_TYPE_INTEGER;
+	params[1].integer.value = INTEL_DSM_REVISION_ID;
+	params[2].type = ACPI_TYPE_INTEGER;
+	params[2].integer.value = INTEL_DSM_FN_PLATFORM_MUX_INFO;
+	params[3].type = ACPI_TYPE_INTEGER;
+	params[3].integer.value = 0;
+
+	ret = acpi_evaluate_object(intel_dsm_priv.dhandle, "_DSM", &input,
+				   &output);
+	if (ret) {
+		DRM_DEBUG_DRIVER("failed to evaluate _DSM: %d\n", ret);
+		goto out;
+	}
+
+	pkg = (union acpi_object *)output.pointer;
+
+	if (pkg->type == ACPI_TYPE_PACKAGE) {
+		union acpi_object *connector_count = &pkg->package.elements[0];
+		DRM_DEBUG_DRIVER("MUX info connectors: %lld\n",
+			  (unsigned long long)connector_count->integer.value);
+		for (i = 1; i < pkg->package.count; i++) {
+			union acpi_object *obj = &pkg->package.elements[i];
+			union acpi_object *connector_id =
+				&obj->package.elements[0];
+			union acpi_object *info = &obj->package.elements[1];
+			DRM_DEBUG_DRIVER("Connector id: 0x%016llx\n",
+				  (unsigned long long)connector_id->integer.value);
+			DRM_DEBUG_DRIVER("  port id: %s\n",
+			       intel_dsm_port_name(info->buffer.pointer[0]));
+			DRM_DEBUG_DRIVER("  display mux info: %s\n",
+			       intel_dsm_mux_type(info->buffer.pointer[1]));
+			DRM_DEBUG_DRIVER("  aux/dc mux info: %s\n",
+			       intel_dsm_mux_type(info->buffer.pointer[2]));
+			DRM_DEBUG_DRIVER("  hpd mux info: %s\n",
+			       intel_dsm_mux_type(info->buffer.pointer[3]));
+		}
+	} else {
+		DRM_ERROR("MUX INFO call failed\n");
+	}
+
+out:
+	kfree(output.pointer);
+}
+
+static int intel_dsm_switchto(enum vga_switcheroo_client_id id)
+{
+	return 0;
+}
+
+static int intel_dsm_power_state(enum vga_switcheroo_client_id id,
+				   enum vga_switcheroo_state state)
+{
+	return 0;
+}
+
+static int intel_dsm_init(void)
+{
+	return 0;
+}
+
+static int intel_dsm_get_client_id(struct pci_dev *pdev)
+{
+	if (intel_dsm_priv.dhandle == DEVICE_ACPI_HANDLE(&pdev->dev))
+		return VGA_SWITCHEROO_IGD;
+	else
+		return VGA_SWITCHEROO_DIS;
+}
+
+static struct vga_switcheroo_handler intel_dsm_handler = {
+	.switchto = intel_dsm_switchto,
+	.power_state = intel_dsm_power_state,
+	.init = intel_dsm_init,
+	.get_client_id = intel_dsm_get_client_id,
+};
+
+static bool intel_dsm_pci_probe(struct pci_dev *pdev)
+{
+	acpi_handle dhandle, intel_handle;
+	acpi_status status;
+	int ret;
+	u32 result;
+
+	dhandle = DEVICE_ACPI_HANDLE(&pdev->dev);
+	if (!dhandle)
+		return false;
+
+	status = acpi_get_handle(dhandle, "_DSM", &intel_handle);
+	if (ACPI_FAILURE(status)) {
+		DRM_ERROR("no _DSM method for intel device\n");
+		return false;
+	}
+
+	ret = intel_dsm(dhandle, INTEL_DSM_FN_SUPPORTED_FUNCTIONS, 0, &result);
+	if (ret < 0) {
+		DRM_ERROR("failed to get supported _DSM functions\n");
+		return false;
+	}
+
+	intel_dsm_priv.dhandle = dhandle;
+
+	intel_dsm_platform_mux_info();
+	return true;
+}
+
+static bool intel_dsm_detect(void)
+{
+	char acpi_method_name[255] = { 0 };
+	struct acpi_buffer buffer = {sizeof(acpi_method_name), acpi_method_name};
+	struct pci_dev *pdev = NULL;
+	int has_dsm = 0;
+	int vga_count = 0;
+
+	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev)) != NULL) {
+		vga_count++;
+
+		has_dsm |= (intel_dsm_pci_probe(pdev) == true);
+	}
+
+	if (vga_count == 2 && has_dsm) {
+		acpi_get_name(intel_dsm_priv.dhandle, ACPI_FULL_PATHNAME, &buffer);
+		DRM_DEBUG_DRIVER("VGA switcheroo: detected DSM switching method %s handle\n",
+		       acpi_method_name);
+		intel_dsm_priv.dsm_detected = true;
+		return true;
+	}
+	return false;
+}
+
+void intel_register_dsm_handler(void)
+{
+	bool r;
+
+	r = intel_dsm_detect();
+	if (!r)
+		return;
+
+	vga_switcheroo_register_handler(&intel_dsm_handler);
+}
+
+void intel_unregister_dsm_handler(void)
+{
+	vga_switcheroo_unregister_handler();
+}
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 6903341..8d7409e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6126,6 +6126,9 @@ void intel_modeset_cleanup(struct drm_device *dev)
 	drm_kms_helper_poll_fini(dev);
 	mutex_lock(&dev->struct_mutex);
 
+	intel_unregister_dsm_handler();
+
+
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
 		/* Skip inactive CRTCs */
 		if (!crtc->fb)
