driver core: Add debug logs for device link related probe deferrals

There's insufficient logging when device links or fw_devlink (waiting to
create device links) cause probe deferrals.  This makes it hard to debug
devices not getting probed. So, add debug logs to make it easy to debug.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20201218031703.3053753-2-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 25e08e5..fe86011 100644 (file)
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -929,6 +929,10 @@ 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);
                mutex_unlock(&fwnode_link_lock);
                return -EPROBE_DEFER;
        }
@@ -943,6 +947,8 @@ 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));
                        ret = -EPROBE_DEFER;
                        break;
                }