ACPI / EC: Fix regression related to PM ops support in ECDT device

On platforms (ASUS X550ZE and possibly all ASUS X series) with valid ECDT
EC but invalid DSDT EC, EC PM ops won't be invoked as ECDT EC is not an
ACPI device. Thus the following commit actually removed post-resume
acpi_ec_enable_event() invocation for such platforms, and triggered a
regression on them that after being resumed, EC (actually should be ECDT)
driver stops handling EC events:

 Commit: c2b46d679b30c5c0d7eb47a21085943242bdd8dc
 Subject: ACPI / EC: Add PM operations to improve event handling for resume process

Notice that the root cause actually is "ECDT is not an ACPI device" rather
than "the timing of acpi_ec_enable_event() invocation", this patch fixes
this issue by enumerating ECDT EC as an ACPI device. Due to the existence
of the noirq stage, the ability of tuning the timing of
acpi_ec_enable_event() invocation is still meaningful.

This patch is a little bit different from the posted fix by moving
acpi_config_boot_ec() from acpi_ec_ecdt_start() to acpi_ec_add() to make
sure that EC event handling won't be stopped as long as the ACPI EC driver
is bound. Thus the following sequence shouldn't disable EC event handling:
unbind,suspend,resume,bind.

Fixes: c2b46d679b30 (ACPI / EC: Add PM operations to improve event handling for resume process)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=196847
Reported-by: Luya Tshimbalanga <luya@fedoraproject.org>
Tested-by: Luya Tshimbalanga <luya@fedoraproject.org>
Cc: 4.9+ <stable@vger.kernel.org> # 4.9+
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 602f8ff212f2..2f2f50322ffb 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1024,6 +1024,9 @@ static void acpi_device_get_busid(struct acpi_device *device)
 	case ACPI_BUS_TYPE_SLEEP_BUTTON:
 		strcpy(device->pnp.bus_id, "SLPF");
 		break;
+	case ACPI_BUS_TYPE_ECDT_EC:
+		strcpy(device->pnp.bus_id, "ECDT");
+		break;
 	default:
 		acpi_get_name(device->handle, ACPI_SINGLE_NAME, &buffer);
 		/* Clean up trailing underscores (if any) */
@@ -1304,6 +1307,9 @@ static void acpi_set_pnp_ids(acpi_handle handle, struct acpi_device_pnp *pnp,
 	case ACPI_BUS_TYPE_SLEEP_BUTTON:
 		acpi_add_id(pnp, ACPI_BUTTON_HID_SLEEPF);
 		break;
+	case ACPI_BUS_TYPE_ECDT_EC:
+		acpi_add_id(pnp, ACPI_ECDT_HID);
+		break;
 	}
 }
 
@@ -2049,6 +2055,21 @@ void acpi_bus_trim(struct acpi_device *adev)
 }
 EXPORT_SYMBOL_GPL(acpi_bus_trim);
 
+int acpi_bus_register_early_device(int type)
+{
+	struct acpi_device *device = NULL;
+	int result;
+
+	result = acpi_add_single_object(&device, NULL,
+					type, ACPI_STA_DEFAULT);
+	if (result)
+		return result;
+
+	device->flags.match_driver = true;
+	return device_attach(&device->dev);
+}
+EXPORT_SYMBOL_GPL(acpi_bus_register_early_device);
+
 static int acpi_bus_scan_fixed(void)
 {
 	int result = 0;