4 files changed, 30 insertions, 5 deletions

diff --git a/drivers/platform/x86/dell-smbios-wmi.c b/drivers/platform/x86/dell-smbios-wmi.c
index 5cf9b13ce6e6..0cab1f9c35af 100644
--- a/drivers/platform/x86/dell-smbios-wmi.c
+++ b/drivers/platform/x86/dell-smbios-wmi.c
@@ -151,8 +151,9 @@ static int dell_smbios_wmi_probe(struct wmi_device *wdev)
         int count;
         int ret;
 
-        if (!wmi_has_guid(DELL_WMI_DESCRIPTOR_GUID))
-                return -ENODEV;
+        ret = dell_wmi_get_descriptor_valid();
+        if (ret)
+                return ret;
 
         priv = devm_kzalloc(&wdev->dev, sizeof(struct wmi_smbios_priv),
                             GFP_KERNEL);
diff --git a/drivers/platform/x86/dell-wmi-descriptor.c b/drivers/platform/x86/dell-wmi-descriptor.c
index 28ef5f37cfbf..4dfef1f53481 100644
--- a/drivers/platform/x86/dell-wmi-descriptor.c
+++ b/drivers/platform/x86/dell-wmi-descriptor.c
@@ -21,14 +21,26 @@
 #include <linux/wmi.h>
 #include "dell-wmi-descriptor.h"
 
+#define DELL_WMI_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012-B622A1EF5492"
+
 struct descriptor_priv {
         struct list_head list;
         u32 interface_version;
         u32 size;
 };
+static int descriptor_valid = -EPROBE_DEFER;
 static LIST_HEAD(wmi_list);
 static DEFINE_MUTEX(list_mutex);
 
+int dell_wmi_get_descriptor_valid(void)
+{
+        if (!wmi_has_guid(DELL_WMI_DESCRIPTOR_GUID))
+                return -ENODEV;
+
+        return descriptor_valid;
+}
+EXPORT_SYMBOL_GPL(dell_wmi_get_descriptor_valid);
+
 bool dell_wmi_get_interface_version(u32 *version)
 {
         struct descriptor_priv *priv;
@@ -91,6 +103,7 @@ static int dell_wmi_descriptor_probe(struct wmi_device *wdev)
         if (obj->type != ACPI_TYPE_BUFFER) {
                 dev_err(&wdev->dev, "Dell descriptor has wrong type\n");
                 ret = -EINVAL;
+                descriptor_valid = ret;
                 goto out;
         }
 
@@ -102,6 +115,7 @@ static int dell_wmi_descriptor_probe(struct wmi_device *wdev)
                         "Dell descriptor buffer has unexpected length (%d)\n",
                         obj->buffer.length);
                 ret = -EINVAL;
+                descriptor_valid = ret;
                 goto out;
         }
 
@@ -111,8 +125,10 @@ static int dell_wmi_descriptor_probe(struct wmi_device *wdev)
                 dev_err(&wdev->dev, "Dell descriptor buffer has invalid signature (%8ph)\n",
                         buffer);
                 ret = -EINVAL;
+                descriptor_valid = ret;
                 goto out;
         }
+        descriptor_valid = 0;
 
         if (buffer[2] != 0 && buffer[2] != 1)
                 dev_warn(&wdev->dev, "Dell descriptor buffer has unknown version (%lu)\n",
diff --git a/drivers/platform/x86/dell-wmi-descriptor.h b/drivers/platform/x86/dell-wmi-descriptor.h
index 5f7b69c2c83a..1e8cb96ffd78 100644
--- a/drivers/platform/x86/dell-wmi-descriptor.h
+++ b/drivers/platform/x86/dell-wmi-descriptor.h
@@ -13,7 +13,13 @@
 
 #include <linux/wmi.h>
 
-#define DELL_WMI_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012-B622A1EF5492"
+/* possible return values:
+ *  -ENODEV: Descriptor GUID missing from WMI bus
+ *  -EPROBE_DEFER: probing for dell-wmi-descriptor not yet run
+ *  0: valid descriptor, successfully probed
+ *  < 0: invalid descriptor, don't probe dependent devices
+ */
+int dell_wmi_get_descriptor_valid(void);
 
 bool dell_wmi_get_interface_version(u32 *version);
 bool dell_wmi_get_size(u32 *size);
diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c
index 54321080a30d..39d2f4518483 100644
--- a/drivers/platform/x86/dell-wmi.c
+++ b/drivers/platform/x86/dell-wmi.c
@@ -655,9 +655,11 @@ static int dell_wmi_events_set_enabled(bool enable)
 static int dell_wmi_probe(struct wmi_device *wdev)
 {
         struct dell_wmi_priv *priv;
+        int ret;
 
-        if (!wmi_has_guid(DELL_WMI_DESCRIPTOR_GUID))
-                return -ENODEV;
+        ret = dell_wmi_get_descriptor_valid();
+        if (ret)
+                return ret;
 
         priv = devm_kzalloc(
                 &wdev->dev, sizeof(struct dell_wmi_priv), GFP_KERNEL);