[PATCH v2] platform/wmi: Allow wmi module to load when acpi_disabled is set

[Hans de Goede]

The core wmi module provides symbols which may be used by other modules.
These other modules may still function when acpi_disabled is set, but
the current behavior of acpi_wmi_init() returning -ENODEV when it is set
causes loading these modules to fail because the wmi module these depend
on fails to load with -ENODEV.

One example of this is booting a kernel with both DT and ACPI/WMI support
on an arm64 systems with devicetree which will lead to acpi_disabled being
set. Trying to load the amdgpu module will fail in this case because it
uses symbols from the drivers/acpi/video module which in turn uses symbols
from the wmi module. Note the video module itself already contains handling
to still load when acpi_disables is set for similar reasons.

Fix this by allowing the wmi module to still load and also register
the class and bus instances since some exported functions like
wmi_driver_register() rely on these being valid.

Fixes: e2c1b56f3dfa ("platform/x86: wmi: Move WMI core code into a separate directory")
Reviewed-by: Armin Wolf <W_Armin at gmx.de>
Signed-off-by: Hans de Goede <johannes.goede at oss.qualcomm.com>
---
Changes in v2:
- Add Reviewed-by + Fixes tags
---
 drivers/platform/wmi/core.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/platform/wmi/core.c b/drivers/platform/wmi/core.c
index a99da9b7039d..ec1a51f08e02 100644
--- a/drivers/platform/wmi/core.c
+++ b/drivers/platform/wmi/core.c
@@ -1598,9 +1598,6 @@ static int __init acpi_wmi_init(void)
 {
 	int error;
 
-	if (acpi_disabled)
-		return -ENODEV;
-
 	error = class_register(&wmi_bus_class);
 	if (error)
 		return error;
@@ -1609,6 +1606,9 @@ static int __init acpi_wmi_init(void)
 	if (error)
 		goto err_unreg_class;
 
+	if (acpi_disabled)
+		return 0;
+
 	error = platform_driver_register(&acpi_wmi_driver);
 	if (error) {
 		pr_err("Error loading mapper\n");
@@ -1628,7 +1628,8 @@ static int __init acpi_wmi_init(void)
 
 static void __exit acpi_wmi_exit(void)
 {
-	platform_driver_unregister(&acpi_wmi_driver);
+	if (!acpi_disabled)
+		platform_driver_unregister(&acpi_wmi_driver);
 	bus_unregister(&wmi_bus_type);
 	class_unregister(&wmi_bus_class);
 }
-- 
2.56.0