linux-kernel - [PATCH net-next v3 1/8] net: dsa: vsc73xx: use read_poll

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Message-Id: <20230912122201.3752918-2-paweldembicki@gmail.com>
Date:   Tue, 12 Sep 2023 14:21:55 +0200
From:   Pawel Dembicki <paweldembicki@...il.com>
To:     netdev@...r.kernel.org
Cc:     Dan Carpenter <dan.carpenter@...aro.org>,
        Simon Horman <simon.horman@...igine.com>,
        Pawel Dembicki <paweldembicki@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, linux-kernel@...r.kernel.org
Subject: [PATCH net-next v3 1/8] net: dsa: vsc73xx: use read_poll_timeout instead delay loop

This commit switches delay loop to read_poll_timeout macro during
Arbiter empty check in adjust link function.

As Russel King suggested:

"This [change] avoids the issue that on the last iteration, the code reads
the register, test it, find the condition that's being waiting for is
false, _then_ waits and end up printing the error message - that last
wait is rather useless, and as the arbiter state isn't checked after
waiting, it could be that we had success during the last wait."

It also remove one short msleep delay.

Suggested-by: Russell King <linux@...linux.org.uk>
Signed-off-by: Pawel Dembicki <paweldembicki@...il.com>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
---
v3:
  - Add "Reviewed-by" to commit message only
v2:
  - introduced patch

 drivers/net/dsa/vitesse-vsc73xx-core.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/drivers/net/dsa/vitesse-vsc73xx-core.c b/drivers/net/dsa/vitesse-vsc73xx-core.c
index 4f09e7438f3b..b117c0c18e36 100644
--- a/drivers/net/dsa/vitesse-vsc73xx-core.c
+++ b/drivers/net/dsa/vitesse-vsc73xx-core.c
@@ -779,7 +779,7 @@ static void vsc73xx_adjust_link(struct dsa_switch *ds, int port,
 	 * after a PHY or the CPU port comes up or down.
 	 */
 	if (!phydev->link) {
-		int maxloop = 10;
+		int ret, err;
 
 		dev_dbg(vsc->dev, "port %d: went down\n",
 			port);
@@ -794,19 +794,16 @@ static void vsc73xx_adjust_link(struct dsa_switch *ds, int port,
 				    VSC73XX_ARBDISC, BIT(port), BIT(port));
 
 		/* Wait until queue is empty */
-		vsc73xx_read(vsc, VSC73XX_BLOCK_ARBITER, 0,
-			     VSC73XX_ARBEMPTY, &val);
-		while (!(val & BIT(port))) {
-			msleep(1);
-			vsc73xx_read(vsc, VSC73XX_BLOCK_ARBITER, 0,
-				     VSC73XX_ARBEMPTY, &val);
-			if (--maxloop == 0) {
-				dev_err(vsc->dev,
-					"timeout waiting for block arbiter\n");
-				/* Continue anyway */
-				break;
-			}
-		}
+		ret = read_poll_timeout(vsc73xx_read, err,
+					err < 0 || (val & BIT(port)),
+					1000, 10000, false,
+					vsc, VSC73XX_BLOCK_ARBITER, 0,
+					VSC73XX_ARBEMPTY, &val);
+		if (ret)
+			dev_err(vsc->dev,
+				"timeout waiting for block arbiter\n");
+		else if (err < 0)
+			dev_err(vsc->dev, "error reading arbiter\n");
 
 		/* Put this port into reset */
 		vsc73xx_write(vsc, VSC73XX_BLOCK_MAC, port, VSC73XX_MAC_CFG,
-- 
2.34.1