linux-kernel - [PATCH 1/3] driver core: Set deferred probe reason when deferred by driver core

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Date:   Wed, 15 Sep 2021 10:28:05 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Saravana Kannan <saravanak@...gle.com>, kernel-team@...roid.com,
        linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH 1/3] driver core: Set deferred probe reason when deferred by
 driver core

When the driver core defers the probe of a device, set the deferred
probe reason so that it's easier to debug. The deferred probe reason is
available in debugfs under devices_deferred.

Signed-off-by: Saravana Kannan <saravanak@...gle.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
---
 drivers/base/core.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 21d4cb5d3767..bf008040b101 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -975,6 +975,7 @@ int device_links_check_suppliers(struct device *dev)
 {
 	struct device_link *link;
 	int ret = 0;
+	struct fwnode_handle *sup_fw;
 
 	/*
 	 * Device waiting for supplier to become available is not allowed to
@@ -983,10 +984,11 @@ int device_links_check_suppliers(struct device *dev)
 	mutex_lock(&fwnode_link_lock);
 	if (dev->fwnode && !list_empty(&dev->fwnode->suppliers) &&
 	    !fw_devlink_is_permissive()) {
-		dev_dbg(dev, "probe deferral - wait for supplier %pfwP\n",
-			list_first_entry(&dev->fwnode->suppliers,
-			struct fwnode_link,
-			c_hook)->supplier);
+		sup_fw = list_first_entry(&dev->fwnode->suppliers,
+					  struct fwnode_link,
+					  c_hook)->supplier;
+		dev_err_probe(dev, -EPROBE_DEFER, "wait for supplier %pfwP\n",
+			      sup_fw);
 		mutex_unlock(&fwnode_link_lock);
 		return -EPROBE_DEFER;
 	}
@@ -1001,8 +1003,9 @@ int device_links_check_suppliers(struct device *dev)
 		if (link->status != DL_STATE_AVAILABLE &&
 		    !(link->flags & DL_FLAG_SYNC_STATE_ONLY)) {
 			device_links_missing_supplier(dev);
-			dev_dbg(dev, "probe deferral - supplier %s not ready\n",
-				dev_name(link->supplier));
+			dev_err_probe(dev, -EPROBE_DEFER,
+				      "supplier %s not ready\n",
+				      dev_name(link->supplier));
 			ret = -EPROBE_DEFER;
 			break;
 		}
-- 
2.33.0.309.g3052b89438-goog