ACPI: Clarify resource conflict message

The message "ACPI: Device needs an ACPI driver" is misleading. The
device _may_ need an ACPI driver, if the BIOS implemented a custom
API for the device in question (which, AFAIK, can't be checked.) If
not, then either a generic ACPI driver may be used (for example
"thermal"), or nothing can be done (other than a white list).

I propose to reword the message to:

ACPI: If an ACPI driver is available for this device, you should use
it instead of the native driver

which I think is more correct. Comments and suggestions welcome.

I also added a message warning about possible problems and system
instability when users pass acpi_enforce_resources=lax, as suggested
by Len.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Thomas Renninger <trenn@suse.de>
Cc: Alan Jenkins <sourcejedi.lkml@googlemail.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/osl.c

@@ -1161,7 +1161,13 @@ int acpi_check_resource_conflict(struct resource *res)
 			       res_list_elem->name,
 			       (long long) res_list_elem->start,
 			       (long long) res_list_elem->end);
-			printk(KERN_INFO "ACPI: Device needs an ACPI driver\n");
+			if (acpi_enforce_resources == ENFORCE_RESOURCES_LAX)
+				printk(KERN_NOTICE "ACPI: This conflict may"
+				       " cause random problems and system"
+				       " instability\n");
+			printk(KERN_INFO "ACPI: If an ACPI driver is available"
+			       " for this device, you should use it instead of"
+			       " the native driver\n");
 		}
 		if (acpi_enforce_resources == ENFORCE_RESOURCES_STRICT)
 			return -EBUSY;