linux-kernel - [PATCH 1/1] firmware: add a function to load optional firmware

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Message-Id: <20180309221243.15489-2-andresx7@gmail.com>
Date:   Fri,  9 Mar 2018 17:12:43 -0500
From:   Andres Rodriguez <andresx7@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     andresx7@...il.com, gregkh@...uxfoundation.org, mcgrof@...nel.org
Subject: [PATCH 1/1] firmware: add a function to load optional firmware

Currently the firmware loader only exposes one silent path for querying
optional firmware, and that is request_firmware_direct(). This function
also disables the usermodehelper fallback which might not always be the
desired behaviour.

This patch introduces request_firmware_optional(), which will not
produce error/warning messages if the firmware file is not found, but
will still attempt to query the usermodehelper for the optional
firmware. Effectively, FW_OPT_UEVENT | FW_OPT_FALLBACK | FW_OPT_NO_WARN.

Signed-off-by: Andres Rodriguez <andresx7@...il.com>
---
 drivers/base/firmware_class.c | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 7dd36ace6152..a5a4dfb90e2f 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -1181,7 +1181,7 @@ static int fw_sysfs_fallback(struct firmware *fw, const char *name,
 	if (!fw_run_sysfs_fallback(opt_flags))
 		return ret;
 
-	dev_warn(device, "Falling back to user helper\n");
+	dev_warn(device, "Falling back to user helper for %s\n", name);
 	return fw_load_from_user_helper(fw, name, device, opt_flags);
 }
 #else /* CONFIG_FW_LOADER_USER_HELPER */
@@ -1351,6 +1351,31 @@ request_firmware(const struct firmware **firmware_p, const char *name,
 }
 EXPORT_SYMBOL(request_firmware);
 
+/**
+ * request_firmware_optional: - request for an optional fw module
+ * @firmware_p: 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.
+ **/
+int
+request_firmware_optional(const struct firmware **firmware_p, const char *name,
+			  struct device *device)
+{
+	int ret;
+
+	/* Need to pin this module until return */
+	__module_get(THIS_MODULE);
+	ret = _request_firmware(firmware_p, name, device, NULL, 0,
+				FW_OPT_UEVENT | FW_OPT_FALLBACK |
+				FW_OPT_NO_WARN);
+	module_put(THIS_MODULE);
+	return ret;
+}
+EXPORT_SYMBOL(request_firmware_optional);
+
 /**
  * request_firmware_direct: - load firmware directly without usermode helper
  * @firmware_p: pointer to firmware image
-- 
2.14.1