ACPI: HED: Always initialize before evged

When the HED driver is built-in, it initializes after evged because they
both are at the same initcall level, so the initialization ordering
depends on the Makefile order. However, this prevents RAS records
coming in between the evged driver initialization and the HED driver
initialization from being handled.

If the number of such RAS records is above the APEI HEST error source
number, the HEST resources may be exhausted, and that may affect
subsequent RAS error reporting.

To fix this issue, change the initcall level of HED to subsys_initcall
and prevent the driver from being built as a module by changing ACPI_HED
in Kconfig from "tristate" to "bool".

Signed-off-by: Xiaofei Tan <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/acpi/Kconfig

···
 	  the modules will be called sbs and sbshc.
 
 config ACPI_HED
-	tristate "Hardware Error Device"
+	bool "Hardware Error Device"
 	help
 	  This driver supports the Hardware Error Device (PNP0C33),
 	  which is used to report some hardware errors notified via

drivers/acpi/hed.c

···
 		.remove = acpi_hed_remove,
 	},
 };
-module_acpi_driver(acpi_hed_driver);
+
+static int __init acpi_hed_driver_init(void)
+{
+	return acpi_bus_register_driver(&acpi_hed_driver);
+}
+subsys_initcall(acpi_hed_driver_init);
 
 MODULE_AUTHOR("Huang Ying");
 MODULE_DESCRIPTION("ACPI Hardware Error Device Driver");