From:   Pin-yen Lin <treapking@chromium.org>
To:     Andrzej Hajda <andrzej.hajda@intel.com>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Robert Foss <rfoss@kernel.org>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Daniel Scally <djrscally@gmail.com>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Prashant Malani <pmalani@chromium.org>,
        Benson Leung <bleung@chromium.org>,
        Guenter Roeck <groeck@chromium.org>
Cc:     Pin-yen Lin <treapking@chromium.org>, linux-kernel@vger.kernel.org,
        Hsin-Yi Wang <hsinyi@chromium.org>,
        Marek Vasut <marex@denx.de>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        dri-devel@lists.freedesktop.org, Xin Ji <xji@analogixsemi.com>,
        Lyude Paul <lyude@redhat.com>,
        Allen Chen <allen.chen@ite.com.tw>, devicetree@vger.kernel.org,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        =?UTF-8?q?N=C3=ADcolas=20F=20=2E=20R=20=2E=20A=20=2E=20Prado?= 
        <nfraprado@collabora.com>, chrome-platform@lists.linux.dev,
        Javier Martinez Canillas <javierm@redhat.com>,
        linux-acpi@vger.kernel.org, Stephen Boyd <swboyd@chromium.org>,
        Chen-Yu Tsai <wenst@chromium.org>
Subject: [PATCH v12 02/10] platform/chrome: cros_ec_typec: Purge blocking switch devlinks
Date:   Tue, 21 Feb 2023 17:50:46 +0800
Message-Id: <20230221095054.1868277-3-treapking@chromium.org>
In-Reply-To: <20230221095054.1868277-1-treapking@chromium.org>
References: <20230221095054.1868277-1-treapking@chromium.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Prashant Malani <pmalani@chromium.org>

When using OF graph, the fw_devlink code will create links between the
individual port driver (cros-ec-typec here) and the parent device for
a Type-C switch (like mode-switch). Since the mode-switch will in turn
have the usb-c-connector (i.e the child of the port driver) as a
supplier, fw_devlink will not be able to resolve the cyclic dependency
correctly.

As a result, the mode-switch driver probe() never runs, so mode-switches
are never registered. Because of that, the port driver probe constantly
fails with -EPROBE_DEFER, because the Type-C connector class requires all
switch devices to be registered prior to port registration.

To break this deadlock and allow the mode-switch registration to occur,
purge all the usb-c-connector nodes' absent suppliers. This eliminates
the connector as a supplier for a switch and allows it to be probed.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: Pin-yen Lin <treapking@chromium.org>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

---

(no changes since v11)

Changes in v11:
- Collected Acked-by tag

Changes in v10:
- Collected Reviewed-by and Tested-by tags

Changes in v7:
- Fix the long comment lines

Changes in v6:
- New in v6

 drivers/platform/chrome/cros_ec_typec.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
index 001b0de95a46..bbc95a3ba5a7 100644
--- a/drivers/platform/chrome/cros_ec_typec.c
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -385,6 +385,16 @@ static int cros_typec_init_ports(struct cros_typec_data *typec)
 		return -EINVAL;
 	}
 
+	/*
+	 * OF graph may have set up some device links with switches,
+	 * since connectors have their own compatible. Purge these
+	 * to avoid a deadlock in switch probe (the switch mistakenly
+	 * assumes the connector is a supplier).
+	 */
+	if (dev_of_node(dev))
+		device_for_each_child_node(dev, fwnode)
+			fw_devlink_purge_absent_suppliers(fwnode);
+
 	/* DT uses "reg" to specify port number. */
 	port_prop = dev->of_node ? "reg" : "port-number";
 	device_for_each_child_node(dev, fwnode) {
-- 
2.39.2.637.g21b0678d19-goog