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Commit 84b5c4fe authored by Luis R. Rodriguez's avatar Luis R. Rodriguez Committed by Greg Kroah-Hartman
Browse files

firmware_loader: document firmware_sysfs_fallback() 



This also sets the expecations for future fallback interfaces, even
if they are not exported.

Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarLuis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent cf1cde7c

drivers/base/firmware_loader/fallback.c

+20 −0
Original line number Diff line number Diff line
@@ -662,6 +662,26 @@ static bool fw_run_sysfs_fallback(enum fw_opt opt_flags) 
	return fw_force_sysfs_fallback(opt_flags);

}



/**

 * 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,