thinkpad-acpi: be more strict when detecting a ThinkPad

Use stricter checks to decide that we're running on a supported ThinkPad.
This should remove some possible false positives, although nobody ever
bothered to report any.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 13 insertions, 9 deletions

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index cc4155c3620e..d69ab3f0bdbc 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -1621,6 +1621,9 @@ static void tpacpi_remove_driver_attributes(struct device_driver *drv)
  *
  *  Sources: IBM ThinkPad Public Web Documents (update changelogs),
  *  Information from users in ThinkWiki
+ *
+ *  WARNING: we use this table also to detect that the machine is
+ *  a ThinkPad in some cases, so don't remove entries lightly.
  */
 
 #define TPV_Q(__v, __id1, __id2, __bv1, __bv2)          \
@@ -1782,6 +1785,12 @@ static void __init tpacpi_check_outdated_fw(void)
         }
 }
 
+static bool __init tpacpi_is_fw_known(void)
+{
+        return tpacpi_check_quirks(tpacpi_bios_version_qtable,
+                        ARRAY_SIZE(tpacpi_bios_version_qtable)) != 0;
+}
+
 /****************************************************************************
  ****************************************************************************
  *
@@ -7706,9 +7715,11 @@ static int __init probe_for_thinkpad(void)
 
         /*
          * Non-ancient models have better DMI tagging, but very old models
-         * don't.
+         * don't.  tpacpi_is_fw_known() is a cheat to help in that case.
          */
-        is_thinkpad = (thinkpad_id.model_str != NULL);
+        is_thinkpad = (thinkpad_id.model_str != NULL) ||
+                      (thinkpad_id.ec_model != 0) ||
+                      tpacpi_is_fw_known();
 
         /* ec is required because many other handles are relative to it */
         TPACPI_ACPIHANDLE_INIT(ec);
@@ -7719,13 +7730,6 @@ static int __init probe_for_thinkpad(void)
                 return -ENODEV;
         }
 
-        /*
-         * Risks a regression on very old machines, but reduces potential
-         * false positives a damn great deal
-         */
-        if (!is_thinkpad)
-                is_thinkpad = (thinkpad_id.vendor == PCI_VENDOR_ID_IBM);
-
         if (!is_thinkpad && !force_load)
                 return -ENODEV;