Merge tag 'driver-core-4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the driver core patchset for 4.18-rc1.

  The large chunk of these are firmware core documentation and api
  updates. Nothing major there, just better descriptions for others to
  be able to understand the firmware code better. There's also a user
  for a new firmware api call.

  Other than that, there are some minor updates for debugfs, kernfs, and
  the driver core itself.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'driver-core-4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (23 commits)
  driver core: hold dev's parent lock when needed
  driver-core: return EINVAL error instead of BUG_ON()
  driver core: add __printf verification to device_create_groups_vargs
  mm: memory_hotplug: use put_device() if device_register fail
  base: core: fix typo 'can by' to 'can be'
  debugfs: inode: debugfs_create_dir uses mode permission from parent
  debugfs: Re-use kstrtobool_from_user()
  Documentation: clarify firmware_class provenance and why we can't rename the module
  Documentation: remove stale firmware API reference
  Documentation: fix few typos and clarifications for the firmware loader
  ath10k: re-enable the firmware fallback mechanism for testmode
  ath10k: use firmware_request_nowarn() to load firmware
  firmware: add firmware_request_nowarn() - load firmware without warnings
  firmware_loader: make firmware_fallback_sysfs() print more useful
  firmware_loader: move kconfig FW_LOADER entries to its own file
  firmware_loader: replace ---help--- with help
  firmware_loader: enhance Kconfig documentation over FW_LOADER
  firmware_loader: document firmware_sysfs_fallback()
  firmware: rename fw_sysfs_fallback to firmware_fallback_sysfs()
  firmware: use () to terminate kernel-doc function names
  ...

11 files changed, 329 insertions, 136 deletions

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 29b0eb4..3e63a90 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -70,81 +70,25 @@ config STANDALONE
 	  If unsure, say Y.
 
 config PREVENT_FIRMWARE_BUILD
-	bool "Prevent firmware from being built"
+	bool "Disable drivers features which enable custom firmware building"
 	default y
 	help
-	  Say yes to avoid building firmware. Firmware is usually shipped
-	  with the driver and only when updating the firmware should a
-	  rebuild be made.
-	  If unsure, say Y here.
-
-config FW_LOADER
-	tristate "Userspace firmware loading support" if EXPERT
-	default y
-	---help---
-	  This option is provided for the case where none of the in-tree modules
-	  require userspace firmware loading support, but a module built
-	  out-of-tree does.
-
-config EXTRA_FIRMWARE
-	string "External firmware blobs to build into the kernel binary"
-	depends on FW_LOADER
-	help
-	  Various drivers in the kernel source tree may require firmware,
-	  which is generally available in your distribution's linux-firmware
-	  package.
-
-	  The linux-firmware package should install firmware into
-	  /lib/firmware/ on your system, so they can be loaded by userspace
-	  helpers on request.
-
-	  This option allows firmware to be built into the kernel for the case
-	  where the user either cannot or doesn't want to provide it from
-	  userspace at runtime (for example, when the firmware in question is
-	  required for accessing the boot device, and the user doesn't want to
-	  use an initrd).
-
-	  This option is a string and takes the (space-separated) names of the
-	  firmware files -- the same names that appear in MODULE_FIRMWARE()
-	  and request_firmware() in the source. These files should exist under
-	  the directory specified by the EXTRA_FIRMWARE_DIR option, which is
-	  /lib/firmware by default.
-
-	  For example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin", copy
-	  the usb8388.bin file into /lib/firmware, and build the kernel. Then
-	  any request_firmware("usb8388.bin") will be satisfied internally
-	  without needing to call out to userspace.
-
-	  WARNING: If you include additional firmware files into your binary
-	  kernel image that are not available under the terms of the GPL,
-	  then it may be a violation of the GPL to distribute the resulting
-	  image since it combines both GPL and non-GPL work. You should
-	  consult a lawyer of your own before distributing such an image.
-
-config EXTRA_FIRMWARE_DIR
-	string "Firmware blobs root directory"
-	depends on EXTRA_FIRMWARE != ""
-	default "/lib/firmware"
-	help
-	  This option controls the directory in which the kernel build system
-	  looks for the firmware files listed in the EXTRA_FIRMWARE option.
-
-config FW_LOADER_USER_HELPER
-	bool
-
-config FW_LOADER_USER_HELPER_FALLBACK
-	bool "Fallback user-helper invocation for firmware loading"
-	depends on FW_LOADER
-	select FW_LOADER_USER_HELPER
-	help
-	  This option enables / disables the invocation of user-helper
-	  (e.g. udev) for loading firmware files as a fallback after the
-	  direct file loading in kernel fails.  The user-mode helper is
-	  no longer required unless you have a special firmware file that
-	  resides in a non-standard path. Moreover, the udev support has
-	  been deprecated upstream.
-
-	  If you are unsure about this, say N here.
+	  Say yes to disable driver features which enable building a custom
+	  driver firmware at kernel build time. These drivers do not use the
+	  kernel firmware API to load firmware (CONFIG_FW_LOADER), instead they
+	  use their own custom loading mechanism. The required firmware is
+	  usually shipped with the driver, building the driver firmware
+	  should only be needed if you have an updated firmware source.
+
+	  Firmware should not be being built as part of kernel, these days
+	  you should always prevent this and say Y here. There are only two
+	  old drivers which enable building of its firmware at kernel build
+	  time:
+
+	    o CONFIG_WANXL through CONFIG_WANXL_BUILD_FIRMWARE
+	    o CONFIG_SCSI_AIC79XX through CONFIG_AIC79XX_BUILD_FIRMWARE
+
+source "drivers/base/firmware_loader/Kconfig"
 
 config WANT_DEV_COREDUMP
 	bool
diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index ef61833..8bfd27e 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -184,10 +184,10 @@ static ssize_t unbind_store(struct device_driver *drv, const char *buf,
 
 	dev = bus_find_device_by_name(bus, NULL, buf);
 	if (dev && dev->driver == drv) {
-		if (dev->parent)	/* Needed for USB */
+		if (dev->parent && dev->bus->need_parent_lock)
 			device_lock(dev->parent);
 		device_release_driver(dev);
-		if (dev->parent)
+		if (dev->parent && dev->bus->need_parent_lock)
 			device_unlock(dev->parent);
 		err = count;
 	}
@@ -211,12 +211,12 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf,
 
 	dev = bus_find_device_by_name(bus, NULL, buf);
 	if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
-		if (dev->parent)	/* Needed for USB */
+		if (dev->parent && bus->need_parent_lock)
 			device_lock(dev->parent);
 		device_lock(dev);
 		err = driver_probe_device(drv, dev);
 		device_unlock(dev);
-		if (dev->parent)
+		if (dev->parent && bus->need_parent_lock)
 			device_unlock(dev->parent);
 
 		if (err > 0) {
@@ -735,10 +735,10 @@ static int __must_check bus_rescan_devices_helper(struct device *dev,
 	int ret = 0;
 
 	if (!dev->driver) {
-		if (dev->parent)	/* Needed for USB */
+		if (dev->parent && dev->bus->need_parent_lock)
 			device_lock(dev->parent);
 		ret = device_attach(dev);
-		if (dev->parent)
+		if (dev->parent && dev->bus->need_parent_lock)
 			device_unlock(dev->parent);
 	}
 	return ret < 0 ? ret : 0;
@@ -770,10 +770,10 @@ EXPORT_SYMBOL_GPL(bus_rescan_devices);
 int device_reprobe(struct device *dev)
 {
 	if (dev->driver) {
-		if (dev->parent)        /* Needed for USB */
+		if (dev->parent && dev->bus->need_parent_lock)
 			device_lock(dev->parent);
 		device_release_driver(dev);
-		if (dev->parent)
+		if (dev->parent && dev->bus->need_parent_lock)
 			device_unlock(dev->parent);
 	}
 	return bus_rescan_devices_helper(dev, NULL);
diff --git a/drivers/base/core.c b/drivers/base/core.c
index ad7b508..36622b5 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1487,7 +1487,7 @@ class_dir_create_and_add(struct class *class, struct kobject *parent_kobj)
 
 	dir = kzalloc(sizeof(*dir), GFP_KERNEL);
 	if (!dir)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	dir->class = class;
 	kobject_init(&dir->kobj, &class_dir_ktype);
@@ -1497,7 +1497,7 @@ class_dir_create_and_add(struct class *class, struct kobject *parent_kobj)
 	retval = kobject_add(&dir->kobj, parent_kobj, "%s", class->name);
 	if (retval < 0) {
 		kobject_put(&dir->kobj);
-		return NULL;
+		return ERR_PTR(retval);
 	}
 	return &dir->kobj;
 }
@@ -1804,6 +1804,10 @@ int device_add(struct device *dev)
 
 	parent = get_device(dev->parent);
 	kobj = get_device_parent(dev, parent);
+	if (IS_ERR(kobj)) {
+		error = PTR_ERR(kobj);
+		goto parent_error;
+	}
 	if (kobj)
 		dev->kobj.parent = kobj;
 
@@ -1902,6 +1906,7 @@ done:
 	kobject_del(&dev->kobj);
  Error:
 	cleanup_glue_dir(dev, glue_dir);
+parent_error:
 	put_device(parent);
 name_error:
 	kfree(dev->p);
@@ -2426,7 +2431,7 @@ static void device_create_release(struct device *dev)
 	kfree(dev);
 }
 
-static struct device *
+static __printf(6, 0) struct device *
 device_create_groups_vargs(struct class *class, struct device *parent,
 			   dev_t devt, void *drvdata,
 			   const struct attribute_group **groups,
@@ -2704,7 +2709,7 @@ static int device_move_class_links(struct device *dev,
 /**
  * device_move - moves a device to a new parent
  * @dev: the pointer to the struct device to be moved
- * @new_parent: the new parent of the device (can by NULL)
+ * @new_parent: the new parent of the device (can be NULL)
  * @dpm_order: how to reorder the dpm_list
  */
 int device_move(struct device *dev, struct device *new_parent,
@@ -2721,6 +2726,11 @@ int device_move(struct device *dev, struct device *new_parent,
 	device_pm_lock();
 	new_parent = get_device(new_parent);
 	new_parent_kobj = get_device_parent(dev, new_parent);
+	if (IS_ERR(new_parent_kobj)) {
+		error = PTR_ERR(new_parent_kobj);
+		put_device(new_parent);
+		goto out;
+	}
 
 	pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev),
 		 __func__, new_parent ? dev_name(new_parent) : "<NULL>");
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index a41c91b..fb4e2df 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -814,13 +814,13 @@ static int __driver_attach(struct device *dev, void *data)
 		return ret;
 	} /* ret > 0 means positive match */
 
-	if (dev->parent)	/* Needed for USB */
+	if (dev->parent && dev->bus->need_parent_lock)
 		device_lock(dev->parent);
 	device_lock(dev);
 	if (!dev->driver)
 		driver_probe_device(drv, dev);
 	device_unlock(dev);
-	if (dev->parent)
+	if (dev->parent && dev->bus->need_parent_lock)
 		device_unlock(dev->parent);
 
 	return 0;
@@ -916,7 +916,7 @@ void device_release_driver_internal(struct device *dev,
 				    struct device_driver *drv,
 				    struct device *parent)
 {
-	if (parent)
+	if (parent && dev->bus->need_parent_lock)
 		device_lock(parent);
 
 	device_lock(dev);
@@ -924,7 +924,7 @@ void device_release_driver_internal(struct device *dev,
 		__device_release_driver(dev, parent);
 
 	device_unlock(dev);
-	if (parent)
+	if (parent && dev->bus->need_parent_lock)
 		device_unlock(parent);
 }
 
diff --git a/drivers/base/driver.c b/drivers/base/driver.c
index ba91255..857c8f1 100644
--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -148,7 +148,11 @@ int driver_register(struct device_driver *drv)
 	int ret;
 	struct device_driver *other;
 
-	BUG_ON(!drv->bus->p);
+	if (!drv->bus->p) {
+		pr_err("Driver '%s' was unable to register with bus_type '%s' because the bus was not initialized.\n",
+			   drv->name, drv->bus->name);
+		return -EINVAL;
+	}
 
 	if ((drv->bus->probe && drv->probe) ||
 	    (drv->bus->remove && drv->remove) ||
diff --git a/drivers/base/firmware_loader/Kconfig b/drivers/base/firmware_loader/Kconfig
new file mode 100644
index 0000000..eb15d97
--- /dev/null
+++ b/drivers/base/firmware_loader/Kconfig
@@ -0,0 +1,154 @@
+menu "Firmware loader"
+
+config FW_LOADER
+	tristate "Firmware loading facility" if EXPERT
+	default y
+	help
+	  This enables the firmware loading facility in the kernel. The kernel
+	  will first look for built-in firmware, if it has any. Next, it will
+	  look for the requested firmware in a series of filesystem paths:
+
+		o firmware_class path module parameter or kernel boot param
+		o /lib/firmware/updates/UTS_RELEASE
+		o /lib/firmware/updates
+		o /lib/firmware/UTS_RELEASE
+		o /lib/firmware
+
+	  Enabling this feature only increases your kernel image by about
+	  828 bytes, enable this option unless you are certain you don't
+	  need firmware.
+
+	  You typically want this built-in (=y) but you can also enable this
+	  as a module, in which case the firmware_class module will be built.
+	  You also want to be sure to enable this built-in if you are going to
+	  enable built-in firmware (CONFIG_EXTRA_FIRMWARE).
+
+if FW_LOADER
+
+config EXTRA_FIRMWARE
+	string "Build named firmware blobs into the kernel binary"
+	help
+	  Device drivers which require firmware can typically deal with
+	  having the kernel load firmware from the various supported
+	  /lib/firmware/ paths. This option enables you to build into the
+	  kernel firmware files. Built-in firmware searches are preceded
+	  over firmware lookups using your filesystem over the supported
+	  /lib/firmware paths documented on CONFIG_FW_LOADER.
+
+	  This may be useful for testing or if the firmware is required early on
+	  in boot and cannot rely on the firmware being placed in an initrd or
+	  initramfs.
+
+	  This option is a string and takes the (space-separated) names of the
+	  firmware files -- the same names that appear in MODULE_FIRMWARE()
+	  and request_firmware() in the source. These files should exist under
+	  the directory specified by the EXTRA_FIRMWARE_DIR option, which is
+	  /lib/firmware by default.
+
+	  For example, you might set CONFIG_EXTRA_FIRMWARE="usb8388.bin", copy
+	  the usb8388.bin file into /lib/firmware, and build the kernel. Then
+	  any request_firmware("usb8388.bin") will be satisfied internally
+	  inside the kernel without ever looking at your filesystem at runtime.
+
+	  WARNING: If you include additional firmware files into your binary
+	  kernel image that are not available under the terms of the GPL,
+	  then it may be a violation of the GPL to distribute the resulting
+	  image since it combines both GPL and non-GPL work. You should
+	  consult a lawyer of your own before distributing such an image.
+
+config EXTRA_FIRMWARE_DIR
+	string "Firmware blobs root directory"
+	depends on EXTRA_FIRMWARE != ""
+	default "/lib/firmware"
+	help
+	  This option controls the directory in which the kernel build system
+	  looks for the firmware files listed in the EXTRA_FIRMWARE option.
+
+config FW_LOADER_USER_HELPER
+	bool "Enable the firmware sysfs fallback mechanism"
+	help
+	  This option enables a sysfs loading facility to enable firmware
+	  loading to the kernel through userspace as a fallback mechanism
+	  if and only if the kernel's direct filesystem lookup for the
+	  firmware failed using the different /lib/firmware/ paths, or the
+	  path specified in the firmware_class path module parameter, or the
+	  firmware_class path kernel boot parameter if the firmware_class is
+	  built-in. For details on how to work with the sysfs fallback mechanism
+	  refer to Documentation/driver-api/firmware/fallback-mechanisms.rst.
+
+	  The direct filesystem lookup for firmware is always used first now.
+
+	  If the kernel's direct filesystem lookup for firmware fails to find
+	  the requested firmware a sysfs fallback loading facility is made
+	  available and userspace is informed about this through uevents.
+	  The uevent can be suppressed if the driver explicitly requested it,
+	  this is known as the driver using the custom fallback mechanism.
+	  If the custom fallback mechanism is used userspace must always
+	  acknowledge failure to find firmware as the timeout for the fallback
+	  mechanism is disabled, and failed requests will linger forever.
+
+	  This used to be the default firmware loading facility, and udev used
+	  to listen for uvents to load firmware for the kernel. The firmware
+	  loading facility functionality in udev has been removed, as such it
+	  can no longer be relied upon as a fallback mechanism. Linux no longer
+	  relies on or uses a fallback mechanism in userspace. If you need to
+	  rely on one refer to the permissively licensed firmwared:
+
+	  https://github.com/teg/firmwared
+
+	  Since this was the default firmware loading facility at one point,
+	  old userspace may exist which relies upon it, and as such this
+	  mechanism can never be removed from the kernel.
+
+	  You should only enable this functionality if you are certain you
+	  require a fallback mechanism and have a userspace mechanism ready to
+	  load firmware in case it is not found. One main reason for this may
+	  be if you have drivers which require firmware built-in and for
+	  whatever reason cannot place the required firmware in initramfs.
+	  Another reason kernels may have this feature enabled is to support a
+	  driver which explicitly relies on this fallback mechanism. Only two
+	  drivers need this today:
+
+	    o CONFIG_LEDS_LP55XX_COMMON
+	    o CONFIG_DELL_RBU
+
+	  Outside of supporting the above drivers, another reason for needing
+	  this may be that your firmware resides outside of the paths the kernel
+	  looks for and cannot possibly be specified using the firmware_class
+	  path module parameter or kernel firmware_class path boot parameter
+	  if firmware_class is built-in.
+
+	  A modern use case may be to temporarily mount a custom partition
+	  during provisioning which is only accessible to userspace, and then
+	  to use it to look for and fetch the required firmware. Such type of
+	  driver functionality may not even ever be desirable upstream by
+	  vendors, and as such is only required to be supported as an interface
+	  for provisioning. Since udev's firmware loading facility has been
+	  removed you can use firmwared or a fork of it to customize how you
+	  want to load firmware based on uevents issued.
+
+	  Enabling this option will increase your kernel image size by about
+	  13436 bytes.
+
+	  If you are unsure about this, say N here, unless you are Linux
+	  distribution and need to support the above two drivers, or you are
+	  certain you need to support some really custom firmware loading
+	  facility in userspace.
+
+config FW_LOADER_USER_HELPER_FALLBACK
+	bool "Force the firmware sysfs fallback mechanism when possible"
+	depends on FW_LOADER_USER_HELPER
+	help
+	  Enabling this option forces a sysfs userspace fallback mechanism
+	  to be used for all firmware requests which explicitly do not disable a
+	  a fallback mechanism. Firmware calls which do prohibit a fallback
+	  mechanism is request_firmware_direct(). This option is kept for
+          backward compatibility purposes given this precise mechanism can also
+	  be enabled by setting the proc sysctl value to true:
+
+	       /proc/sys/kernel/firmware_config/force_sysfs_fallback
+
+	  If you are unsure about this, say N here.
+
+endif # FW_LOADER
+endmenu
diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
index 3583541..b676a99 100644
--- a/drivers/base/firmware_loader/fallback.c
+++ b/drivers/base/firmware_loader/fallback.c
@@ -125,7 +125,7 @@ static ssize_t timeout_show(struct class *class, struct class_attribute *attr,
 }
 
 /**
- * firmware_timeout_store - set number of seconds to wait for firmware
+ * firmware_timeout_store() - set number of seconds to wait for firmware
  * @class: device class pointer
  * @attr: device attribute pointer
  * @buf: buffer to scan for timeout value
@@ -239,7 +239,7 @@ static int map_fw_priv_pages(struct fw_priv *fw_priv)
 }
 
 /**
- * firmware_loading_store - set value in the 'loading' control file
+ * firmware_loading_store() - set value in the 'loading' control file
  * @dev: device pointer
  * @attr: device attribute pointer
  * @buf: buffer to scan for loading control value
@@ -431,7 +431,7 @@ static int fw_realloc_pages(struct fw_sysfs *fw_sysfs, int min_size)
 }
 
 /**
- * firmware_data_write - write method for firmware
+ * firmware_data_write() - write method for firmware
  * @filp: open sysfs file
  * @kobj: kobject for the device
  * @bin_attr: bin_attr structure
@@ -512,7 +512,7 @@ static const struct attribute_group *fw_dev_attr_groups[] = {
 
 static struct fw_sysfs *
 fw_create_instance(struct firmware *firmware, const char *fw_name,
-		   struct device *device, unsigned int opt_flags)
+		   struct device *device, enum fw_opt opt_flags)
 {
 	struct fw_sysfs *fw_sysfs;
 	struct device *f_dev;
@@ -537,7 +537,7 @@ exit:
 }
 
 /**
- * fw_load_sysfs_fallback - load a firmware via the sysfs fallback mechanism
+ * fw_load_sysfs_fallback() - load a firmware via the sysfs fallback mechanism
  * @fw_sysfs: firmware sysfs information for the firmware to load
  * @opt_flags: flags of options, FW_OPT_*
  * @timeout: timeout to wait for the load
@@ -545,7 +545,7 @@ exit:
  * In charge of constructing a sysfs fallback interface for firmware loading.
  **/
 static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs,
-				  unsigned int opt_flags, long timeout)
+				  enum fw_opt opt_flags, long timeout)
 {
 	int retval = 0;
 	struct device *f_dev = &fw_sysfs->dev;
@@ -599,7 +599,7 @@ err_put_dev:
 
 static int fw_load_from_user_helper(struct firmware *firmware,
 				    const char *name, struct device *device,
-				    unsigned int opt_flags)
+				    enum fw_opt opt_flags)
 {
 	struct fw_sysfs *fw_sysfs;
 	long timeout;
@@ -640,7 +640,7 @@ out_unlock:
 	return ret;
 }
 
-static bool fw_force_sysfs_fallback(unsigned int opt_flags)
+static bool fw_force_sysfs_fallback(enum fw_opt opt_flags)
 {
 	if (fw_fallback_config.force_sysfs_fallback)
 		return true;
@@ -649,7 +649,7 @@ static bool fw_force_sysfs_fallback(unsigned int opt_flags)
 	return true;
 }
 
-static bool fw_run_sysfs_fallback(unsigned int opt_flags)
+static bool fw_run_sysfs_fallback(enum fw_opt opt_flags)
 {
 	if (fw_fallback_config.ignore_sysfs_fallback) {
 		pr_info_once("Ignoring firmware sysfs fallback due to sysctl knob\n");
@@ -662,14 +662,39 @@ static bool fw_run_sysfs_fallback(unsigned int opt_flags)
 	return fw_force_sysfs_fallback(opt_flags);
 }
 
-int fw_sysfs_fallback(struct firmware *fw, const char *name,
-		      struct device *device,
-		      unsigned int opt_flags,
-		      int ret)
+/**
+ * firmware_fallback_sysfs() - use the fallback mechanism to find firmware
+ * @fw: pointer to firmware image
+ * @name: name of firmware file to look for
+ * @device: device for which firmware is being loaded
+ * @opt_flags: options to control firmware loading behaviour
+ * @ret: return value from direct lookup which triggered the fallback mechanism
+ *
+ * This function is called if direct lookup for the firmware failed, it enables
+ * a fallback mechanism through userspace by exposing a sysfs loading
+ * interface. Userspace is in charge of loading the firmware through the syfs
+ * loading interface. This syfs fallback mechanism may be disabled completely
+ * on a system by setting the proc sysctl value ignore_sysfs_fallback to true.
+ * If this false we check if the internal API caller set the @FW_OPT_NOFALLBACK
+ * flag, if so it would also disable the fallback mechanism. A system may want
+ * to enfoce the sysfs fallback mechanism at all times, it can do this by
+ * setting ignore_sysfs_fallback to false and force_sysfs_fallback to true.
+ * Enabling force_sysfs_fallback is functionally equivalent to build a kernel
+ * with CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
+ **/
+int firmware_fallback_sysfs(struct firmware *fw, const char *name,
+			    struct device *device,
+			    enum fw_opt opt_flags,
+			    int ret)
 {
 	if (!fw_run_sysfs_fallback(opt_flags))
 		return ret;
 
-	dev_warn(device, "Falling back to user helper\n");
+	if (!(opt_flags & FW_OPT_NO_WARN))
+		dev_warn(device, "Falling back to syfs fallback for: %s\n",
+				 name);
+	else
+		dev_dbg(device, "Falling back to sysfs fallback for: %s\n",
+				name);
 	return fw_load_from_user_helper(fw, name, device, opt_flags);
 }
diff --git a/drivers/base/firmware_loader/fallback.h b/drivers/base/firmware_loader/fallback.h
index f825567..2106350 100644
--- a/drivers/base/firmware_loader/fallback.h
+++ b/drivers/base/firmware_loader/fallback.h
@@ -5,6 +5,8 @@
 #include <linux/firmware.h>
 #include <linux/device.h>
 
+#include "firmware.h"
+
 /**
  * struct firmware_fallback_config - firmware fallback configuration settings
  *
@@ -29,10 +31,10 @@ struct firmware_fallback_config {
 };
 
 #ifdef CONFIG_FW_LOADER_USER_HELPER
-int fw_sysfs_fallback(struct firmware *fw, const char *name,
-		      struct device *device,
-		      unsigned int opt_flags,
-		      int ret);
+int firmware_fallback_sysfs(struct firmware *fw, const char *name,
+			    struct device *device,
+			    enum fw_opt opt_flags,
+			    int ret);
 void kill_pending_fw_fallback_reqs(bool only_kill_custom);
 
 void fw_fallback_set_cache_timeout(void);
@@ -41,10 +43,10 @@ void fw_fallback_set_default_timeout(void);
 int register_sysfs_loader(void);
 void unregister_sysfs_loader(void);
 #else /* CONFIG_FW_LOADER_USER_HELPER */
-static inline int fw_sysfs_fallback(struct firmware *fw, const char *name,
-				    struct device *device,
-				    unsigned int opt_flags,
-				    int ret)
+static inline int firmware_fallback_sysfs(struct firmware *fw, const char *name,
+					  struct device *device,
+					  enum fw_opt opt_flags,
+					  int ret)
 {
 	/* Keep carrying over the same error */
 	return ret;
diff --git a/drivers/base/firmware_loader/firmware.h b/drivers/base/firmware_loader/firmware.h
index 64acbb1..4c1395f 100644
--- a/drivers/base/firmware_loader/firmware.h
+++ b/drivers/base/firmware_loader/firmware.h
@@ -2,6 +2,7 @@
 #ifndef __FIRMWARE_LOADER_H
 #define __FIRMWARE_LOADER_H
 
+#include <linux/bitops.h>
 #include <linux/firmware.h>
 #include <linux/types.h>
 #include <linux/kref.h>
@@ -10,13 +11,33 @@
 
 #include <generated/utsrelease.h>
 
-/* firmware behavior options */
-#define FW_OPT_UEVENT			(1U << 0)
-#define FW_OPT_NOWAIT			(1U << 1)
-#define FW_OPT_USERHELPER		(1U << 2)
-#define FW_OPT_NO_WARN			(1U << 3)
-#define FW_OPT_NOCACHE			(1U << 4)
-#define FW_OPT_NOFALLBACK		(1U << 5)
+/**
+ * enum fw_opt - options to control firmware loading behaviour
+ *
+ * @FW_OPT_UEVENT: Enables the fallback mechanism to send a kobject uevent
+ *	when the firmware is not found. Userspace is in charge to load the
+ *	firmware using the sysfs loading facility.
+ * @FW_OPT_NOWAIT: Used to describe the firmware request is asynchronous.
+ * @FW_OPT_USERHELPER: Enable the fallback mechanism, in case the direct
+ *	filesystem lookup fails at finding the firmware.  For details refer to
+ *	firmware_fallback_sysfs().
+ * @FW_OPT_NO_WARN: Quiet, avoid printing warning messages.
+ * @FW_OPT_NOCACHE: Disables firmware caching. Firmware caching is used to
+ *	cache the firmware upon suspend, so that upon resume races against the
+ *	firmware file lookup on storage is avoided. Used for calls where the
+ *	file may be too big, or where the driver takes charge of its own
+ *	firmware caching mechanism.
+ * @FW_OPT_NOFALLBACK: Disable the fallback mechanism. Takes precedence over
+ *	&FW_OPT_UEVENT and &FW_OPT_USERHELPER.
+ */
+enum fw_opt {
+	FW_OPT_UEVENT =         BIT(0),
+	FW_OPT_NOWAIT =         BIT(1),
+	FW_OPT_USERHELPER =     BIT(2),
+	FW_OPT_NO_WARN =        BIT(3),
+	FW_OPT_NOCACHE =        BIT(4),
+	FW_OPT_NOFALLBACK =     BIT(5),
+};
 
 enum fw_status {
 	FW_STATUS_UNKNOWN,
@@ -110,6 +131,6 @@ static inline void fw_state_done(struct fw_priv *fw_priv)
 }
 
 int assign_fw(struct firmware *fw, struct device *device,
-	      unsigned int opt_flags);
+	      enum fw_opt opt_flags);
 
 #endif /* __FIRMWARE_LOADER_H */
diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
index eb34089e..0943e70 100644
--- a/drivers/base/firmware_loader/main.c
+++ b/drivers/base/firmware_loader/main.c
@@ -443,7 +443,7 @@ static int fw_add_devm_name(struct device *dev, const char *name)
 #endif
 
 int assign_fw(struct firmware *fw, struct device *device,
-	      unsigned int opt_flags)
+	      enum fw_opt opt_flags)
 {
 	struct fw_priv *fw_priv = fw->priv;
 	int ret;
@@ -558,7 +558,7 @@ static void fw_abort_batch_reqs(struct firmware *fw)
 static int
 _request_firmware(const struct firmware **firmware_p, const char *name,
 		  struct device *device, void *buf, size_t size,
-		  unsigned int opt_flags)
+		  enum fw_opt opt_flags)
 {
 	struct firmware *fw = NULL;
 	int ret;
@@ -581,7 +581,7 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
 			dev_warn(device,
 				 "Direct firmware load for %s failed with error %d\n",
 				 name, ret);
-		ret = fw_sysfs_fallback(fw, name, device, opt_flags, ret);
+		ret = firmware_fallback_sysfs(fw, name, device, opt_flags, ret);
 	} else
 		ret = assign_fw(fw, device, opt_flags);
 
@@ -597,7 +597,7 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
 }
 
 /**
- * request_firmware: - send firmware request and wait for it
+ * request_firmware() - send firmware request and wait for it
  * @firmware_p: pointer to firmware image
  * @name: name of firmware file
  * @device: device for which firmware is being loaded
@@ -632,7 +632,34 @@ request_firmware(const struct firmware **firmware_p, const char *name,
 EXPORT_SYMBOL(request_firmware);
 
 /**
- * request_firmware_direct: - load firmware directly without usermode helper
+ * firmware_request_nowarn() - request for an optional fw module
+ * @firmware: pointer to firmware image
+ * @name: name of firmware file
+ * @device: device for which firmware is being loaded
+ *
+ * This function is similar in behaviour to request_firmware(), except
+ * it doesn't produce warning messages when the file is not found.
+ * The sysfs fallback mechanism is enabled if direct filesystem lookup fails,
+ * however, however failures to find the firmware file with it are still
+ * suppressed. It is therefore up to the driver to check for the return value
+ * of this call and to decide when to inform the users of errors.
+ **/
+int firmware_request_nowarn(const struct firmware **firmware, const char *name,
+			    struct device *device)
+{
+	int ret;
+
+	/* Need to pin this module until return */
+	__module_get(THIS_MODULE);
+	ret = _request_firmware(firmware, name, device, NULL, 0,
+				FW_OPT_UEVENT | FW_OPT_NO_WARN);
+	module_put(THIS_MODULE);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(firmware_request_nowarn);
+
+/**
+ * request_firmware_direct() - load firmware directly without usermode helper
  * @firmware_p: pointer to firmware image
  * @name: name of firmware file
  * @device: device for which firmware is being loaded
@@ -657,7 +684,7 @@ int request_firmware_direct(const struct firmware **firmware_p,
 EXPORT_SYMBOL_GPL(request_firmware_direct);
 
 /**
- * firmware_request_cache: - cache firmware for suspend so resume can use it
+ * firmware_request_cache() - cache firmware for suspend so resume can use it
  * @name: name of firmware file
  * @device: device for which firmware should be cached for
  *
@@ -681,7 +708,7 @@ int firmware_request_cache(struct device *device, const char *name)
 EXPORT_SYMBOL_GPL(firmware_request_cache);
 
 /**
- * request_firmware_into_buf - load firmware into a previously allocated buffer
+ * request_firmware_into_buf() - load firmware into a previously allocated buffer
  * @firmware_p: pointer to firmware image
  * @name: name of firmware file
  * @device: device for which firmware is being loaded and DMA region allocated
@@ -713,7 +740,7 @@ request_firmware_into_buf(const struct firmware **firmware_p, const char *name,
 EXPORT_SYMBOL(request_firmware_into_buf);
 
 /**
- * release_firmware: - release the resource associated with a firmware image
+ * release_firmware() - release the resource associated with a firmware image
  * @fw: firmware resource to release
  **/
 void release_firmware(const struct firmware *fw)
@@ -734,7 +761,7 @@ struct firmware_work {
 	struct device *device;
 	void *context;
 	void (*cont)(const struct firmware *fw, void *context);
-	unsigned int opt_flags;
+	enum fw_opt opt_flags;
 };
 
 static void request_firmware_work_func(struct work_struct *work)
@@ -755,7 +782,7 @@ static void request_firmware_work_func(struct work_struct *work)
 }
 
 /**
- * request_firmware_nowait - asynchronous version of request_firmware
+ * request_firmware_nowait() - asynchronous version of request_firmware
  * @module: module requesting the firmware
  * @uevent: sends uevent to copy the firmware image if this flag
  *	is non-zero else the firmware copy must be done manually.
@@ -824,7 +851,7 @@ EXPORT_SYMBOL(request_firmware_nowait);
 static ASYNC_DOMAIN_EXCLUSIVE(fw_cache_domain);
 
 /**
- * cache_firmware - cache one firmware image in kernel memory space
+ * cache_firmware() - cache one firmware image in kernel memory space
  * @fw_name: the firmware image name
  *
  * Cache firmware in kernel memory so that drivers can use it when
@@ -866,7 +893,7 @@ static struct fw_priv *lookup_fw_priv(const char *fw_name)
 }
 
 /**
- * uncache_firmware - remove one cached firmware image
+ * uncache_firmware() - remove one cached firmware image
  * @fw_name: the firmware image name
  *
  * Uncache one firmware image which has been cached successfully
@@ -1042,7 +1069,7 @@ static void __device_uncache_fw_images(void)
 }
 
 /**
- * device_cache_fw_images - cache devices' firmware
+ * device_cache_fw_images() - cache devices' firmware
  *
  * If one device called request_firmware or its nowait version
  * successfully before, the firmware names are recored into the
@@ -1075,7 +1102,7 @@ static void device_cache_fw_images(void)
 }
 
 /**
- * device_uncache_fw_images - uncache devices' firmware
+ * device_uncache_fw_images() - uncache devices' firmware
  *
  * uncache all firmwares which have been cached successfully
  * by device_uncache_fw_images earlier
@@ -1092,7 +1119,7 @@ static void device_uncache_fw_images_work(struct work_struct *work)
 }
 
 /**
- * device_uncache_fw_images_delay - uncache devices firmwares
+ * device_uncache_fw_images_delay() - uncache devices firmwares
  * @delay: number of milliseconds to delay uncache device firmwares
  *
  * uncache all devices's firmwares which has been cached successfully
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index bffe861..f5e5601 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -649,13 +649,19 @@ static const struct attribute_group *memory_memblk_attr_groups[] = {
 static
 int register_memory(struct memory_block *memory)
 {
+	int ret;
+
 	memory->dev.bus = &memory_subsys;
 	memory->dev.id = memory->start_section_nr / sections_per_block;
 	memory->dev.release = memory_block_release;
 	memory->dev.groups = memory_memblk_attr_groups;
 	memory->dev.offline = memory->state == MEM_OFFLINE;
 
-	return device_register(&memory->dev);
+	ret = device_register(&memory->dev);
+	if (ret)
+		put_device(&memory->dev);
+
+	return ret;
 }
 
 static int init_memory_block(struct memory_block **memory,