3 files changed, 73 insertions, 12 deletions

diff --git a/drivers/acpi/acpi_watchdog.c b/drivers/acpi/acpi_watchdog.c
index ebb626ffb5fa..4bde16fb97d8 100644
--- a/drivers/acpi/acpi_watchdog.c
+++ b/drivers/acpi/acpi_watchdog.c
@@ -12,23 +12,64 @@
 #define pr_fmt(fmt) "ACPI: watchdog: " fmt
 
 #include <linux/acpi.h>
+#include <linux/dmi.h>
 #include <linux/ioport.h>
 #include <linux/platform_device.h>
 
 #include "internal.h"
 
+static const struct dmi_system_id acpi_watchdog_skip[] = {
+	{
+		/*
+		 * On Lenovo Z50-70 there are two issues with the WDAT
+		 * table. First some of the instructions use RTC SRAM
+		 * to store persistent information. This does not work well
+		 * with Linux RTC driver. Second, more important thing is
+		 * that the instructions do not actually reset the system.
+		 *
+		 * On this particular system iTCO_wdt seems to work just
+		 * fine so we prefer that over WDAT for now.
+		 *
+		 * See also https://bugzilla.kernel.org/show_bug.cgi?id=199033.
+		 */
+		.ident = "Lenovo Z50-70",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "20354"),
+			DMI_MATCH(DMI_PRODUCT_VERSION, "Lenovo Z50-70"),
+		},
+	},
+	{}
+};
+
+static const struct acpi_table_wdat *acpi_watchdog_get_wdat(void)
+{
+	const struct acpi_table_wdat *wdat = NULL;
+	acpi_status status;
+
+	if (acpi_disabled)
+		return NULL;
+
+	if (dmi_check_system(acpi_watchdog_skip))
+		return NULL;
+
+	status = acpi_get_table(ACPI_SIG_WDAT, 0,
+				(struct acpi_table_header **)&wdat);
+	if (ACPI_FAILURE(status)) {
+		/* It is fine if there is no WDAT */
+		return NULL;
+	}
+
+	return wdat;
+}
+
 /**
  * Returns true if this system should prefer ACPI based watchdog instead of
  * the native one (which are typically the same hardware).
  */
 bool acpi_has_watchdog(void)
 {
-	struct acpi_table_header hdr;
-
-	if (acpi_disabled)
-		return false;
-
-	return ACPI_SUCCESS(acpi_get_table_header(ACPI_SIG_WDAT, 0, &hdr));
+	return !!acpi_watchdog_get_wdat();
 }
 EXPORT_SYMBOL_GPL(acpi_has_watchdog);
 
@@ -41,12 +82,10 @@ void __init acpi_watchdog_init(void)
 	struct platform_device *pdev;
 	struct resource *resources;
 	size_t nresources = 0;
-	acpi_status status;
 	int i;
 
-	status = acpi_get_table(ACPI_SIG_WDAT, 0,
-				(struct acpi_table_header **)&wdat);
-	if (ACPI_FAILURE(status)) {
+	wdat = acpi_watchdog_get_wdat();
+	if (!wdat) {
 		/* It is fine if there is no WDAT */
 		return;
 	}
diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
index e1eee7a60fad..f1cc4f9d31cd 100644
--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -635,4 +635,26 @@ module_param_call(lid_init_state,
 		  NULL, 0644);
 MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
 
-module_acpi_driver(acpi_button_driver);
+static int acpi_button_register_driver(struct acpi_driver *driver)
+{
+	/*
+	 * Modules such as nouveau.ko and i915.ko have a link time dependency
+	 * on acpi_lid_open(), and would therefore not be loadable on ACPI
+	 * capable kernels booted in non-ACPI mode if the return value of
+	 * acpi_bus_register_driver() is returned from here with ACPI disabled
+	 * when this driver is built as a module.
+	 */
+	if (acpi_disabled)
+		return 0;
+
+	return acpi_bus_register_driver(driver);
+}
+
+static void acpi_button_unregister_driver(struct acpi_driver *driver)
+{
+	if (!acpi_disabled)
+		acpi_bus_unregister_driver(driver);
+}
+
+module_driver(acpi_button_driver, acpi_button_register_driver,
+	       acpi_button_unregister_driver);
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index cc234e6a6297..970dd87d347c 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2166,10 +2166,10 @@ int __init acpi_scan_init(void)
 	acpi_cmos_rtc_init();
 	acpi_container_init();
 	acpi_memory_hotplug_init();
+	acpi_watchdog_init();
 	acpi_pnp_init();
 	acpi_int340x_thermal_init();
 	acpi_amba_init();
-	acpi_watchdog_init();
 	acpi_init_lpit();
 
 	acpi_scan_add_handler(&generic_device_handler);