Merge tag 'platform-drivers-x86-v4.15-2' of git://git.infradead.org/linux-platform-drivers-x86

Pull x86 platform driver fixes from Darren Hart:
 "Fix two issues resulting from the dell-smbios refactoring and
  introduction of the dell-smbios-wmi dispatcher.

  The first ensures a proper error code is returned when kzalloc fails.

  The second avoids an issue in older Dell BIOS implementations which
  would fail if the more complex calls were made by limiting those
  platforms to the simple calls such as those used by the existing
  dell-laptop and dell-wmi drivers, preserving their functionality prior
  to the addition of the dell-smbios-wmi dispatcher"

* tag 'platform-drivers-x86-v4.15-2' of git://git.infradead.org/linux-platform-drivers-x86:
  platform/x86: dell-laptop: fix error return code in dell_init()
  platform/x86: dell-smbios-wmi: Disable userspace interface if missing hotfix

drivers/platform/x86/dell-laptop.c

@@ -2074,8 +2074,10 @@ static int __init dell_init(void)
 		goto fail_platform_device2;
 
 	buffer = kzalloc(sizeof(struct calling_interface_buffer), GFP_KERNEL);
-	if (!buffer)
+	if (!buffer) {
+		ret = -ENOMEM;
 		goto fail_buffer;
+	}
 
 
 	ret = dell_setup_rfkill();

drivers/platform/x86/dell-smbios-wmi.c

@@ -147,7 +147,10 @@ static long dell_smbios_wmi_filter(struct wmi_device *wdev, unsigned int cmd,
 
 static int dell_smbios_wmi_probe(struct wmi_device *wdev)
 {
+	struct wmi_driver *wdriver =
+		container_of(wdev->dev.driver, struct wmi_driver, driver);
 	struct wmi_smbios_priv *priv;
+	u32 hotfix;
 	int count;
 	int ret;
 
@@ -164,6 +167,16 @@ static int dell_smbios_wmi_probe(struct wmi_device *wdev)
 	if (!dell_wmi_get_size(&priv->req_buf_size))
 		return -EPROBE_DEFER;
 
+	/* some SMBIOS calls fail unless BIOS contains hotfix */
+	if (!dell_wmi_get_hotfix(&hotfix))
+		return -EPROBE_DEFER;
+	if (!hotfix) {
+		dev_warn(&wdev->dev,
+			"WMI SMBIOS userspace interface not supported(%u), try upgrading to a newer BIOS\n",
+			hotfix);
+		wdriver->filter_callback = NULL;
+	}
+
 	/* add in the length object we will use internally with ioctl */
 	priv->req_buf_size += sizeof(u64);
 	ret = set_required_buffer_size(wdev, priv->req_buf_size);

drivers/platform/x86/dell-wmi-descriptor.c

@@ -27,6 +27,7 @@ struct descriptor_priv {
 	struct list_head list;
 	u32 interface_version;
 	u32 size;
+	u32 hotfix;
 };
 static int descriptor_valid = -EPROBE_DEFER;
 static LIST_HEAD(wmi_list);
@@ -77,6 +78,24 @@ bool dell_wmi_get_size(u32 *size)
 }
 EXPORT_SYMBOL_GPL(dell_wmi_get_size);
 
+bool dell_wmi_get_hotfix(u32 *hotfix)
+{
+	struct descriptor_priv *priv;
+	bool ret = false;
+
+	mutex_lock(&list_mutex);
+	priv = list_first_entry_or_null(&wmi_list,
+					struct descriptor_priv,
+					list);
+	if (priv) {
+		*hotfix = priv->hotfix;
+		ret = true;
+	}
+	mutex_unlock(&list_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dell_wmi_get_hotfix);
+
 /*
  * Descriptor buffer is 128 byte long and contains:
  *
@@ -85,6 +104,7 @@ EXPORT_SYMBOL_GPL(dell_wmi_get_size);
  * Object Signature          4       4    " WMI"
  * WMI Interface Version     8       4    <version>
  * WMI buffer length        12       4    <length>
+ * WMI hotfix number        16       4    <hotfix>
  */
 static int dell_wmi_descriptor_probe(struct wmi_device *wdev)
 {
@@ -144,15 +164,17 @@ static int dell_wmi_descriptor_probe(struct wmi_device *wdev)
 
 	priv->interface_version = buffer[2];
 	priv->size = buffer[3];
+	priv->hotfix = buffer[4];
 	ret = 0;
 	dev_set_drvdata(&wdev->dev, priv);
 	mutex_lock(&list_mutex);
 	list_add_tail(&priv->list, &wmi_list);
 	mutex_unlock(&list_mutex);
 
-	dev_dbg(&wdev->dev, "Detected Dell WMI interface version %lu and buffer size %lu\n",
+	dev_dbg(&wdev->dev, "Detected Dell WMI interface version %lu, buffer size %lu, hotfix %lu\n",
 		(unsigned long) priv->interface_version,
-		(unsigned long) priv->size);
+		(unsigned long) priv->size,
+		(unsigned long) priv->hotfix);
 
 out:
 	kfree(obj);

drivers/platform/x86/dell-wmi-descriptor.h

@@ -23,5 +23,6 @@ int dell_wmi_get_descriptor_valid(void);
 
 bool dell_wmi_get_interface_version(u32 *version);
 bool dell_wmi_get_size(u32 *size);
+bool dell_wmi_get_hotfix(u32 *hotfix);
 
 #endif