[PATCH v6 04/13] firmware_loader: document firmware_sysfs_fallback()
From: "Luis R. Rodriguez" <mcgrof@kernel.org>
Date: 2018-05-08 18:12:38
Also in:
linux-fsdevel, linux-scsi, linux-wireless, lkml
Subsystem:
driver core, kobjects, debugfs and sysfs, firmware loader (request_firmware), the rest · Maintainers:
Greg Kroah-Hartman, "Rafael J. Wysocki", Danilo Krummrich, Luis Chamberlain, Russ Weight, Linus Torvalds
This also sets the expecations for future fallback interfaces, even if they are not exported. Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> --- drivers/base/firmware_loader/fallback.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)
diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
index 3db9e0f225ac..9169e7b9800c 100644
--- a/drivers/base/firmware_loader/fallback.c
+++ b/drivers/base/firmware_loader/fallback.c@@ -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,
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2.17.0