netdev - [PATCH net] net: sfp: return the number of written bytes for smbus single byte access

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Message-ID: <20260105151840.144552-1-maxime.chevallier@bootlin.com>
Date: Mon,  5 Jan 2026 16:18:39 +0100
From: Maxime Chevallier <maxime.chevallier@...tlin.com>
To: davem@...emloft.net,
	Andrew Lunn <andrew@...n.ch>,
	Jakub Kicinski <kuba@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Paolo Abeni <pabeni@...hat.com>,
	Russell King <linux@...linux.org.uk>,
	Jonas Jelonek <jelonek.jonas@...il.com>,
	Heiner Kallweit <hkallweit1@...il.com>
Cc: Maxime Chevallier <maxime.chevallier@...tlin.com>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	thomas.petazzoni@...tlin.com,
	Florian Fainelli <f.fainelli@...il.com>,
	Köry Maincent <kory.maincent@...tlin.com>,
	Simon Horman <horms@...nel.org>,
	Romain Gantois <romain.gantois@...tlin.com>,
	Marek Behún <kabel@...nel.org>
Subject: [PATCH net] net: sfp: return the number of written bytes for smbus single byte access

We expect the SFP write accessors to return the number of written bytes.
We fail to do so for single-byte smbus accesses, which may cause errors
when setting a module's high-power state and for some cotsworks modules.

Let's return the amount of written bytes, as expected.

Fixes: 7662abf4db94 ("net: phy: sfp: Add support for SMBus module access")
Signed-off-by: Maxime Chevallier <maxime.chevallier@...tlin.com>
---
 drivers/net/phy/sfp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
index 6166e9196364..84bef5099dda 100644
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -765,7 +765,7 @@ static int sfp_smbus_byte_write(struct sfp *sfp, bool a2, u8 dev_addr,
 		dev_addr++;
 	}
 
-	return 0;
+	return data - (u8 *)buf;
 }
 
 static int sfp_i2c_configure(struct sfp *sfp, struct i2c_adapter *i2c)
-- 
2.49.0