@@ -1495,20 +1495,9 @@ int phylink_of_phy_connect(struct phylink *pl, struct device_node *dn,
}
EXPORT_SYMBOL_GPL(phylink_of_phy_connect);
-/**
- * phylink_fwnode_phy_connect() - connect the PHY specified in the fwnode.
- * @pl: a pointer to a &struct phylink returned from phylink_create()
- * @fwnode: a pointer to a &struct fwnode_handle.
- * @flags: PHY-specific flags to communicate to the PHY device driver
- *
- * Connect the phy specified @fwnode to the phylink instance specified
- * by @pl.
- *
- * Returns 0 on success or a negative errno.
- */
-int phylink_fwnode_phy_connect(struct phylink *pl,
- struct fwnode_handle *fwnode,
- u32 flags)
+static int __phylink_fwnode_phy_connect(struct phylink *pl,
+ struct fwnode_handle *fwnode,
+ u32 flags, bool probe)
{
struct fwnode_handle *phy_fwnode;
struct phy_device *phy_dev;
@@ -1530,8 +1519,21 @@ int phylink_fwnode_phy_connect(struct phylink *pl,
phy_dev = fwnode_phy_find_device(phy_fwnode);
/* We're done with the phy_node handle */
fwnode_handle_put(phy_fwnode);
- if (!phy_dev)
- return -ENODEV;
+ if (!phy_dev) {
+ /* Drivers that connect to the PHY from ndo_open do not support
+ * waiting for the PHY to defer probe now, because doing so
+ * would propagate -EPROBE_DEFER to user space, which is an
+ * error code the kernel does not export.
+ */
+ if (!probe)
+ return -ENODEV;
+
+ /* Allow the PHY driver to defer probing, and return -ENODEV if
+ * it times out or if we know it will never become available.
+ */
+ ret = driver_deferred_probe_check_state(pl->dev);
+ return ret == -EPROBE_DEFER ? ret : -ENODEV;
+ }
/* Use PHY device/driver interface */
if (pl->link_interface == PHY_INTERFACE_MODE_NA) {
@@ -1552,6 +1554,45 @@ int phylink_fwnode_phy_connect(struct phylink *pl,
return ret;
}
+
+/**
+ * phylink_of_phy_connect_probe() - connect the PHY in the DT node during probe.
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @dn: a pointer to a &struct device_node.
+ * @flags: PHY-specific flags to communicate to the PHY device driver
+ *
+ * Performs the same action as %phylink_of_phy_connect(), but allows the PHY
+ * driver to defer probing, and propagates -EPROBE_DEFER to the caller.
+ * This function cannot be called from contexts that propagate the return code
+ * to user space.
+ *
+ * Returns 0 on success or a negative errno.
+ */
+int phylink_of_phy_connect_probe(struct phylink *pl, struct device_node *dn,
+ u32 flags)
+{
+ return __phylink_fwnode_phy_connect(pl, of_fwnode_handle(dn), flags,
+ true);
+}
+EXPORT_SYMBOL_GPL(phylink_of_phy_connect_probe);
+
+/**
+ * phylink_fwnode_phy_connect() - connect the PHY specified in the fwnode.
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @fwnode: a pointer to a &struct fwnode_handle.
+ * @flags: PHY-specific flags to communicate to the PHY device driver
+ *
+ * Connect the phy specified @fwnode to the phylink instance specified
+ * by @pl.
+ *
+ * Returns 0 on success or a negative errno.
+ */
+int phylink_fwnode_phy_connect(struct phylink *pl,
+ struct fwnode_handle *fwnode,
+ u32 flags)
+{
+ return __phylink_fwnode_phy_connect(pl, fwnode, flags, false);
+}
EXPORT_SYMBOL_GPL(phylink_fwnode_phy_connect);
/**
@@ -531,6 +531,8 @@ void phylink_destroy(struct phylink *);
int phylink_connect_phy(struct phylink *, struct phy_device *);
int phylink_of_phy_connect(struct phylink *, struct device_node *, u32 flags);
+int phylink_of_phy_connect_probe(struct phylink *pl, struct device_node *dn,
+ u32 flags);
int phylink_fwnode_phy_connect(struct phylink *pl,
struct fwnode_handle *fwnode,
u32 flags);
phylink_fwnode_phy_connect() relies on fwnode_phy_find_device(), which does not have insight into why a PHY is missing, it just returns NULL, case in which the connect returns -ENODEV. So there seems to be no handling of probe deferral for the MDIO bus driver, PHY driver, etc, there is an implicit assumption that these have all been bound before the phy_connect() call. This is probably why so many drivers do the PHY connect operation from ndo_open() rather than at boot time, to maximize the chances of the PHY driver having been probed. Normally fw_devlink enforces automatic device links based on OF phandles, and this simply blocks the consumer (Ethernet controller, user of phylink) driver from probing, rather than letting it probe just to get an -EPROBE_DEFER when the supplier (PHY driver) is unavailable). However support for "phy-handle" is sporadic, most recently having been removed in commit 3782326577d4 ("Revert "of: property: fw_devlink: Add support for "phy-handle" property""). So practically, rather than relying on fw_devlink, it is desirable for callers of phylink_fwnode_phy_connect() to consider that PHY drivers might defer probing, and apply backpressure on their own probe if they can. The approach we take is to use driver_deferred_probe_check_state(), which basically decides whether to defer probe based on whether it is still possible for a driver to become available. If not, we return the same old -ENODEV as before (a return value some callers have come to expect). As a consequence of this change, during boot (up to the late_initcall stage), we will wait slightly longer for a PHY that is truly missing before declaring it absent. Before, a phylink user that called phy_connect() from probe was worse off than one who did so from ndo_open(). But with the change, it is actually better, because PHY probe deferral during the nfsroot case is better treated with connect-at-probe than with connect-at-open. Russell King points out that -EPROBE_DEFER is not exported to user space, and drivers who connect at probe may propagate the phylink phy_connect() call to user space. So we need to create a new entry point into phylink, used only by drivers which guarantee they do not propagate this error to user space, only use it for backpressure purposes. It's hard to put the blame on a commit since this functionality never worked, but there is also a sense of urgency to backport this change to stable kernels. The reason being new DT compatibility with old kernels. A PHY may have a missing supplier (IRQ parent) described in DT which has no driver on an old kernel. fwnode_mdiobus_phy_device_register() handles this to the extent that the PHY defers probe until the late_initcall stage, then it gives up and falls back to poll mode. We need to wait for that PHY driver to fall back, and not return -ENODEV early while it is still waiting for its IRQ to become available (which never will). So the blamed commit chosen is the oldest one where this change will apply. Fixes: 25396f680dd6 ("net: phylink: introduce phylink_fwnode_phy_connect()") Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> --- drivers/net/phy/phylink.c | 73 ++++++++++++++++++++++++++++++--------- include/linux/phylink.h | 2 ++ 2 files changed, 59 insertions(+), 16 deletions(-)