linux-kernel - [PATCH] platform/chrome: cros_ec_typec: allow deferred probe of switch handles

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Date:   Mon, 23 Jan 2023 09:36:20 +0000
From:   Victor Ding <victording@...omium.org>
To:     linux-kernel@...r.kernel.org, chrome-platform@...ts.linux.dev
Cc:     gustavoars@...nel.org, heikki.krogerus@...ux.intel.com,
        dnojiri@...omium.org, dustin@...ett.net, lee.jones@...aro.org,
        tzungbi@...nel.org, groeck@...omium.org,
        gregkh@...uxfoundation.org, pmalani@...omium.org,
        tinghan.shen@...iatek.com, sebastian.reichel@...labora.com,
        enric.balletbo@...labora.com, bleung@...omium.org,
        Victor Ding <victording@...omium.org>
Subject: [PATCH] platform/chrome: cros_ec_typec: allow deferred probe of switch handles

`fwnode_typec_{retimer,mux,switch}_get()` could return `-EPROBE_DEFER`,
which is called from `cros_typec_get_switch_handles`. When this happens,
it does not indicate absence of switches; instead, it only hints that
probing of switches should occur at a later time.

Progagate `-EPROBE_DEFER` to upper layer logic so that they can re-try
probing switches as a better time.

Signed-off-by: Victor Ding <victording@...omium.org>
---

 drivers/platform/chrome/cros_ec_typec.c | 30 +++++++++++++++++--------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
index 59de4ce01fab..f4b3fc788491 100644
--- a/drivers/platform/chrome/cros_ec_typec.c
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -145,31 +145,37 @@ static int cros_typec_get_switch_handles(struct cros_typec_port *port,
 					 struct fwnode_handle *fwnode,
 					 struct device *dev)
 {
+	int ret = 0;
+
 	port->mux = fwnode_typec_mux_get(fwnode, NULL);
 	if (IS_ERR(port->mux)) {
-		dev_dbg(dev, "Mux handle not found.\n");
+		ret = PTR_ERR(port->mux);
+		dev_dbg(dev, "Mux handle not found: %d.\n", ret);
 		goto mux_err;
 	}
 
 	port->retimer = fwnode_typec_retimer_get(fwnode);
 	if (IS_ERR(port->retimer)) {
-		dev_dbg(dev, "Retimer handle not found.\n");
+		ret = PTR_ERR(port->retimer);
+		dev_dbg(dev, "Retimer handle not found: %d.\n", ret);
 		goto retimer_sw_err;
 	}
 
 	port->ori_sw = fwnode_typec_switch_get(fwnode);
 	if (IS_ERR(port->ori_sw)) {
-		dev_dbg(dev, "Orientation switch handle not found.\n");
+		ret = PTR_ERR(port->ori_sw);
+		dev_dbg(dev, "Orientation switch handle not found: %d\n", ret);
 		goto ori_sw_err;
 	}
 
 	port->role_sw = fwnode_usb_role_switch_get(fwnode);
 	if (IS_ERR(port->role_sw)) {
-		dev_dbg(dev, "USB role switch handle not found.\n");
+		ret = PTR_ERR(port->role_sw);
+		dev_dbg(dev, "USB role switch handle not found: %d\n", ret);
 		goto role_sw_err;
 	}
 
-	return 0;
+	return ret;
 
 role_sw_err:
 	typec_switch_put(port->ori_sw);
@@ -181,7 +187,7 @@ static int cros_typec_get_switch_handles(struct cros_typec_port *port,
 	typec_mux_put(port->mux);
 	port->mux = NULL;
 mux_err:
-	return -ENODEV;
+	return ret;
 }
 
 static int cros_typec_add_partner(struct cros_typec_data *typec, int port_num,
@@ -423,9 +429,15 @@ static int cros_typec_init_ports(struct cros_typec_data *typec)
 		}
 
 		ret = cros_typec_get_switch_handles(cros_port, fwnode, dev);
-		if (ret)
-			dev_dbg(dev, "No switch control for port %d\n",
-				port_num);
+		switch (ret) {
+		case 0:
+			break;
+		case -EPROBE_DEFER:
+			dev_err(dev, "Deferring getting switch handles at port %d\n", port_num);
+			goto unregister_ports;
+		default:
+			dev_dbg(dev, "No switch control for port %d, err: %d\n", port_num, ret);
+		}
 
 		ret = cros_typec_register_port_altmodes(typec, port_num);
 		if (ret) {
-- 
2.39.0.246.g2a6d74b583-goog