From: "Luis R. Rodriguez" <mcgrof@kernel•org>
To: gregkh@linuxfoundation•org
Cc: akpm@linux-foundation•org, keescook@chromium•org,
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Subject: [PATCH v5 4/6] firmware_loader: document firmware_sysfs_fallback()
Date: Fri, 4 May 2018 10:43:53 -0700 [thread overview]
Message-ID: <20180504174356.13227-5-mcgrof@kernel.org> (raw)
In-Reply-To: <20180504174356.13227-1-mcgrof@kernel.org>
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,
--
2.17.0
next prev parent reply other threads:[~2018-05-04 17:43 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-04 17:43 [PATCH v5 0/6] firmware_loader: cleanups for v4.18 Luis R. Rodriguez
2018-05-04 17:43 ` [PATCH v5 1/6] firmware: wrap FW_OPT_* into an enum Luis R. Rodriguez
2018-05-04 17:43 ` [PATCH v5 2/6] firmware: use () to terminate kernel-doc function names Luis R. Rodriguez
2018-05-04 17:43 ` [PATCH v5 3/6] firmware: rename fw_sysfs_fallback to firmware_fallback_sysfs() Luis R. Rodriguez
2018-05-04 17:43 ` Luis R. Rodriguez [this message]
2018-05-04 17:43 ` [PATCH v5 5/6] firmware_loader: enhance Kconfig documentation over FW_LOADER Luis R. Rodriguez
2018-05-04 17:43 ` [PATCH v5 6/6] firmware_loader: move kconfig FW_LOADER entries to its own file Luis R. Rodriguez
2018-05-04 19:17 ` [PATCH v5 0/6] firmware_loader: cleanups for v4.18 Krzysztof Halasa
2018-05-04 19:58 ` Luis R. Rodriguez
2018-05-05 20:26 ` Krzysztof Halasa
2018-05-08 15:24 ` Luis R. Rodriguez
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