Merge tag 'acpi-4.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull ACPI fix from Rafael Wysocki:
 "A recently introduced boot regression related to the ACPI EC
  initialization is addressed by restoring the previous behavior (Lv
  Zheng)"

* tag 'acpi-4.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI / EC: Fix a boot EC regresion by restoring boot EC support for the DSDT EC

drivers/acpi/bus.c

@@ -1051,7 +1051,7 @@ static int __init acpi_bus_init(void)
 	 * Maybe EC region is required at bus_scan/acpi_get_devices. So it
 	 * is necessary to enable it as early as possible.
 	 */
-	acpi_boot_ec_enable();
+	acpi_ec_dsdt_probe();
 
 	printk(KERN_INFO PREFIX "Interpreter enabled\n");
 

drivers/acpi/ec.c

@@ -1446,10 +1446,30 @@ ec_parse_io_ports(struct acpi_resource *resource, void *context)
 	return AE_OK;
 }
 
-int __init acpi_boot_ec_enable(void)
+static const struct acpi_device_id ec_device_ids[] = {
+	{"PNP0C09", 0},
+	{"", 0},
+};
+
+int __init acpi_ec_dsdt_probe(void)
 {
-	if (!boot_ec)
+	acpi_status status;
+
+	if (boot_ec)
 		return 0;
+
+	/*
+	 * Finding EC from DSDT if there is no ECDT EC available. When this
+	 * function is invoked, ACPI tables have been fully loaded, we can
+	 * walk namespace now.
+	 */
+	boot_ec = make_acpi_ec();
+	if (!boot_ec)
+		return -ENOMEM;
+	status = acpi_get_devices(ec_device_ids[0].id,
+				  ec_parse_device, boot_ec, NULL);
+	if (ACPI_FAILURE(status) || !boot_ec->handle)
+		return -ENODEV;
 	if (!ec_install_handlers(boot_ec)) {
 		first_ec = boot_ec;
 		return 0;
@@ -1457,11 +1477,6 @@ int __init acpi_boot_ec_enable(void)
 	return -EFAULT;
 }
 
-static const struct acpi_device_id ec_device_ids[] = {
-	{"PNP0C09", 0},
-	{"", 0},
-};
-
 #if 0
 /*
  * Some EC firmware variations refuses to respond QR_EC when SCI_EVT is not

drivers/acpi/internal.h

@@ -181,7 +181,7 @@ typedef int (*acpi_ec_query_func) (void *data);
 
 int acpi_ec_init(void);
 int acpi_ec_ecdt_probe(void);
-int acpi_boot_ec_enable(void);
+int acpi_ec_dsdt_probe(void);
 void acpi_ec_block_transactions(void);
 void acpi_ec_unblock_transactions(void);
 void acpi_ec_unblock_transactions_early(void);