From: Maxime Chevallier <maxime.chevallier@bootlin.com>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: davem@davemloft.net, "Andrew Lunn" <andrew@lunn.ch>,
"Jakub Kicinski" <kuba@kernel.org>,
"Eric Dumazet" <edumazet@google.com>,
"Paolo Abeni" <pabeni@redhat.com>,
"Heiner Kallweit" <hkallweit1@gmail.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
thomas.petazzoni@bootlin.com,
"Florian Fainelli" <f.fainelli@gmail.com>,
"Köry Maincent" <kory.maincent@bootlin.com>,
"Simon Horman" <horms@kernel.org>,
"Romain Gantois" <romain.gantois@bootlin.com>,
"Antoine Tenart" <atenart@kernel.org>,
"Marek Behún" <kabel@kernel.org>,
"Sean Anderson" <sean.anderson@linux.dev>,
"Bjørn Mork" <bjorn@mork.no>
Subject: Re: [PATCH net-next v2 1/2] net: phy: sfp: Add support for SMBus module access
Date: Tue, 25 Feb 2025 19:20:55 +0100 [thread overview]
Message-ID: <20250225192055.32168b48@fedora.home> (raw)
In-Reply-To: <Z74GLblGUPhHID8a@shell.armlinux.org.uk>
On Tue, 25 Feb 2025 18:04:29 +0000
"Russell King (Oracle)" <linux@armlinux.org.uk> wrote:
> On Tue, Feb 25, 2025 at 12:20:39PM +0100, Maxime Chevallier wrote:
> > The SFP module's eeprom and internals are accessible through an i2c bus.
> > However, all the i2c transfers that are performed are SMBus-style
> > transfers for read and write operations.
>
> Note that there are SFPs that fail if you access them by byte - the
> 3FE46541AA locks the bus if you byte access the emulated EEPROM at
> 0x50, address 0x51. This is documented in sfp_sm_mod_probe().
>
> So there's a very real reason for adding the warning - this module
> will not work!
That's indeed pretty serious and since we can't even read the
eeprom, there's not even a chance to have, say, a list of modules that
will break with 1-byte io. So indeed the warning is needed...
Thanks
Maxime
next prev parent reply other threads:[~2025-02-25 18:21 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-25 11:20 [PATCH net-next v2 0/2] net: phy: sfp: Add single-byte SMBus SFP access Maxime Chevallier
2025-02-25 11:20 ` [PATCH net-next v2 1/2] net: phy: sfp: Add support for SMBus module access Maxime Chevallier
2025-02-25 13:41 ` Andrew Lunn
2025-02-25 13:56 ` Maxime Chevallier
2025-02-25 14:58 ` Andrew Lunn
2025-02-25 18:23 ` Russell King (Oracle)
2025-02-25 18:06 ` Russell King (Oracle)
2025-02-25 18:04 ` Russell King (Oracle)
2025-02-25 18:20 ` Maxime Chevallier [this message]
2025-02-25 18:41 ` Sean Anderson
2025-02-25 18:48 ` Maxime Chevallier
2025-03-08 18:42 ` Maxime Chevallier
2025-02-25 11:20 ` [PATCH net-next v2 2/2] net: mdio: mdio-i2c: Add support for single-byte SMBus operations Maxime Chevallier
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