diff --git a/drivers/gpu/drm/radeon/radeon_atpx_handler.c b/drivers/gpu/drm/radeon/radeon_atpx_handler.c
index 950a1ac95d6ad47dd1cc3be2c9da6a01c28d98fc..c1f2671a7b0bb33cb39abaa4228faaddde2e8505 100644
--- a/drivers/gpu/drm/radeon/radeon_atpx_handler.c
+++ b/drivers/gpu/drm/radeon/radeon_atpx_handler.c
@@ -14,17 +14,50 @@
 
 #include "radeon_acpi.h"
 
+struct radeon_atpx_functions {
+	bool px_params;
+	bool power_cntl;
+	bool disp_mux_cntl;
+	bool i2c_mux_cntl;
+	bool switch_start;
+	bool switch_end;
+	bool disp_connectors_mapping;
+	bool disp_detetion_ports;
+};
+
+struct radeon_atpx {
+	struct radeon_atpx_functions functions;
+};
+
 static struct radeon_atpx_priv {
 	bool atpx_detected;
 	/* handle for device - and atpx */
 	acpi_handle dhandle;
 	acpi_handle atpx_handle;
+	struct radeon_atpx atpx;
 } radeon_atpx_priv;
 
-static int radeon_atpx_get_version(acpi_handle handle)
+struct atpx_verify_interface {
+	u16 size;		/* structure size in bytes (includes size field) */
+	u16 version;		/* version */
+	u32 function_bits;	/* supported functions bit vector */
+} __packed;
+
+/**
+ * radeon_atpx_call - call an ATPX method
+ *
+ * @handle: acpi handle
+ * @function: the ATPX function to execute
+ * @params: ATPX function params
+ *
+ * Executes the requested ATPX function (all asics).
+ * Returns a pointer to the acpi output buffer.
+ */
+static union acpi_object *radeon_atpx_call(acpi_handle handle, int function,
+					   struct acpi_buffer *params)
 {
 	acpi_status status;
-	union acpi_object atpx_arg_elements[2], *obj;
+	union acpi_object atpx_arg_elements[2];
 	struct acpi_object_list atpx_arg;
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 
@@ -32,21 +65,96 @@ static int radeon_atpx_get_version(acpi_handle handle)
 	atpx_arg.pointer = &atpx_arg_elements[0];
 
 	atpx_arg_elements[0].type = ACPI_TYPE_INTEGER;
-	atpx_arg_elements[0].integer.value = ATPX_FUNCTION_VERIFY_INTERFACE;
+	atpx_arg_elements[0].integer.value = function;
+
+	if (params) {
+		atpx_arg_elements[1].type = ACPI_TYPE_BUFFER;
+		atpx_arg_elements[1].buffer.length = params->length;
+		atpx_arg_elements[1].buffer.pointer = params->pointer;
+	} else {
+		/* We need a second fake parameter */
+		atpx_arg_elements[1].type = ACPI_TYPE_INTEGER;
+		atpx_arg_elements[1].integer.value = 0;
+	}
 
-	atpx_arg_elements[1].type = ACPI_TYPE_INTEGER;
-	atpx_arg_elements[1].integer.value = 0;
+	status = acpi_evaluate_object(handle, "ATPX", &atpx_arg, &buffer);
 
-	status = acpi_evaluate_object(handle, NULL, &atpx_arg, &buffer);
-	if (ACPI_FAILURE(status)) {
-		printk("%s: failed to call ATPX: %s\n", __func__, acpi_format_exception(status));
-		return -ENOSYS;
+	/* Fail only if calling the method fails and ATPX is supported */
+	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
+		printk("failed to evaluate ATPX got %s\n",
+		       acpi_format_exception(status));
+		kfree(buffer.pointer);
+		return NULL;
 	}
-	obj = (union acpi_object *)buffer.pointer;
-	if (obj && (obj->type == ACPI_TYPE_BUFFER))
-		printk(KERN_INFO "radeon atpx: version is %d\n", *((u8 *)(obj->buffer.pointer) + 2));
-	kfree(buffer.pointer);
-	return 0;
+
+	return buffer.pointer;
+}
+
+/**
+ * radeon_atpx_parse_functions - parse supported functions
+ *
+ * @f: supported functions struct
+ * @mask: supported functions mask from ATPX
+ *
+ * Use the supported functions mask from ATPX function
+ * ATPX_FUNCTION_VERIFY_INTERFACE to determine what functions
+ * are supported (all asics).
+ */
+static void radeon_atpx_parse_functions(struct radeon_atpx_functions *f, u32 mask)
+{
+	f->px_params = mask & ATPX_GET_PX_PARAMETERS_SUPPORTED;
+	f->power_cntl = mask & ATPX_POWER_CONTROL_SUPPORTED;
+	f->disp_mux_cntl = mask & ATPX_DISPLAY_MUX_CONTROL_SUPPORTED;
+	f->i2c_mux_cntl = mask & ATPX_I2C_MUX_CONTROL_SUPPORTED;
+	f->switch_start = mask & ATPX_GRAPHICS_DEVICE_SWITCH_START_NOTIFICATION_SUPPORTED;
+	f->switch_end = mask & ATPX_GRAPHICS_DEVICE_SWITCH_END_NOTIFICATION_SUPPORTED;
+	f->disp_connectors_mapping = mask & ATPX_GET_DISPLAY_CONNECTORS_MAPPING_SUPPORTED;
+	f->disp_detetion_ports = mask & ATPX_GET_DISPLAY_DETECTION_PORTS_SUPPORTED;
+}
+
+/**
+ * radeon_atpx_verify_interface - verify ATPX
+ *
+ * @handle: acpi handle
+ * @atpx: radeon atpx struct
+ *
+ * Execute the ATPX_FUNCTION_VERIFY_INTERFACE ATPX function
+ * to initialize ATPX and determine what features are supported
+ * (all asics).
+ * returns 0 on success, error on failure.
+ */
+static int radeon_atpx_verify_interface(acpi_handle handle,
+					struct radeon_atpx *atpx)
+{
+	union acpi_object *info;
+	struct atpx_verify_interface output;
+	size_t size;
+	int err = 0;
+
+	info = radeon_atpx_call(handle, ATPX_FUNCTION_VERIFY_INTERFACE, NULL);
+	if (!info)
+		return -EIO;
+
+	memset(&output, 0, sizeof(output));
+
+	size = *(u16 *) info->buffer.pointer;
+	if (size < 8) {
+		printk("ATPX buffer is too small: %lu\n", size);
+		err = -EINVAL;
+		goto out;
+	}
+	size = min(sizeof(output), size);
+
+	memcpy(&output, info->buffer.pointer, size);
+
+	/* TODO: check version? */
+	printk("ATPX version %u\n", output.version);
+
+	radeon_atpx_parse_functions(&atpx->functions, output.function_bits);
+
+out:
+	kfree(info);
+	return err;
 }
 
 static int radeon_atpx_execute(acpi_handle handle, int cmd_id, u16 value)
@@ -161,9 +269,8 @@ static bool radeon_atpx_pci_probe_handle(struct pci_dev *pdev)
 static int radeon_atpx_init(void)
 {
 	/* set up the ATPX handle */
-
-	radeon_atpx_get_version(radeon_atpx_priv.atpx_handle);
-	return 0;
+	return radeon_atpx_verify_interface(radeon_atpx_priv.atpx_handle,
+					    &radeon_atpx_priv.atpx);
 }
 
 static int radeon_atpx_get_client_id(struct pci_dev *pdev)