linux-kernel - [PATCH RFC 7/7] usb: typec: ucsi: reorder operations in ucsi_run

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Message-Id: <20240603-ucsi-rework-interface-v1-7-99a6d544cec8@linaro.org>
Date: Mon, 03 Jun 2024 02:25:00 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Maxime Coquelin <mcoquelin.stm32@...il.com>, 
 Alexandre Torgue <alexandre.torgue@...s.st.com>
Cc: Nikita Travkin <nikita@...n.ru>, 
 Neil Armstrong <neil.armstrong@...aro.org>, linux-usb@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com, 
 linux-arm-kernel@...ts.infradead.org
Subject: [PATCH RFC 7/7] usb: typec: ucsi: reorder operations in
 ucsi_run_command()

Streamline control stream of ucsi_run_command(). Reorder operations so
that there is only one call to ucsi_acknowledge(), making sure that all
complete commands are acknowledged. This also makes sure that the
command is acknowledged even if reading MESSAGE_IN data returns an
error.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
---
 drivers/usb/typec/ucsi/ucsi.c | 34 ++++++++++++++--------------------
 1 file changed, 14 insertions(+), 20 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index 4d36a04dc63b..4666dec005a6 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -95,7 +95,7 @@ static int ucsi_acknowledge(struct ucsi *ucsi, bool conn_ack)
 static int ucsi_run_command(struct ucsi *ucsi, u64 command, u32 *cci,
 			    void *data, size_t size, bool conn_ack)
 {
-	int ret;
+	int ret, err;
 
 	*cci = 0;
 
@@ -120,30 +120,24 @@ static int ucsi_run_command(struct ucsi *ucsi, u64 command, u32 *cci,
 	if (!(*cci & UCSI_CCI_COMMAND_COMPLETE))
 		return -EIO;
 
-	if (*cci & UCSI_CCI_NOT_SUPPORTED) {
-		if (ucsi_acknowledge(ucsi, false) < 0)
-			dev_err(ucsi->dev,
-				"ACK of unsupported command failed\n");
-		return -EOPNOTSUPP;
-	}
-
-	if (*cci & UCSI_CCI_ERROR) {
-		/* Acknowledge the command that failed */
-		ret = ucsi_acknowledge(ucsi, false);
-		return ret ? ret : -EIO;
-	}
+	if (*cci & UCSI_CCI_NOT_SUPPORTED)
+		err = -EOPNOTSUPP;
+	else if (*cci & UCSI_CCI_ERROR)
+		err = -EIO;
+	else
+		err = 0;
 
-	if (data) {
-		ret = ucsi->ops->read_message_in(ucsi, data, size);
-		if (ret)
-			return ret;
-	}
+	if (!err && data && UCSI_CCI_LENGTH(*cci))
+		err = ucsi->ops->read_message_in(ucsi, data, size);
 
-	ret = ucsi_acknowledge(ucsi, conn_ack);
+	/*
+	 * Don't ACK connection change if there was an error.
+	 */
+	ret = ucsi_acknowledge(ucsi, err ? false : conn_ack);
 	if (ret)
 		return ret;
 
-	return 0;
+	return err;
 }
 
 static int ucsi_read_error(struct ucsi *ucsi)

-- 
2.39.2