netdev - [RFC PATCH net-next 3/3] net: dsa: allow the phy_connect() call to return -EPROBE

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Date:   Thu,  2 Sep 2021 01:50:53 +0300
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     netdev@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Alvin Šipraga <alsi@...g-olufsen.dk>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        kernel-team <kernel-team@...roid.com>,
        Len Brown <lenb@...nel.org>
Subject: [RFC PATCH net-next 3/3] net: dsa: allow the phy_connect() call to return -EPROBE_DEFER

Currently DSA ignores any errors coming from dsa_port_setup(), and this
includes:

dsa_port_setup
-> dsa_slave_create
   -> dsa_slave_phy_setup
      -> phylink_of_phy_connect
         -> ...
            -> phy_attach_direct

This is done such that PHYs present on optional riser cards which are
missing do not cause the entire switch probing to fail.

Now that phy_attach_direct tries harder to probe the specific PHY driver
instead of genphy, it can actually return -EPROBE_DEFER. It makes sense
to treat this error separately, and not just give up. Trigger the normal
error path, unwind the setup done so far, and come back later.

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 net/dsa/dsa2.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index e78901d33a10..282bdebac835 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -912,6 +912,8 @@ static int dsa_tree_setup_switches(struct dsa_switch_tree *dst)
 
 	list_for_each_entry(dp, &dst->ports, list) {
 		err = dsa_port_setup(dp);
+		if (err == -EPROBE_DEFER)
+			goto teardown;
 		if (err) {
 			dsa_port_devlink_teardown(dp);
 			dp->type = DSA_PORT_TYPE_UNUSED;
-- 
2.25.1