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bh=fLHCu1SzDUA81bfOLrX40HQiaQBQLCEnAu274pcYQI8=; b=CVqql2uZnn25u38xUpnKUfNUVQhNWeQZuyo6ovNiU1q2OF6rFT5LluPVTdNoaKf2ZsujlG VOb37t+gS+AzpzdUlsffmNG0uh1OsUZY2+1GWauWuS4Vi3PaY4WYelX/aJwiaQTd7AtJWe ewCKVjysXsjeSm5CUlMTgoNu6NGL72OEbEzqM6loCbrDNz8ndhEaW8E0MGwsggFhS+3C2S CGRs0VMzSfV6FYN8LfaxQYM87mxjDMwaTCFKj0msLbuErOhH5NcH/jVbf6Bf5ZIG5o96Lj gk8qeb2ljL2AndLEM4VHkx2J2jixaTIqZuC0oUPtajmQSEAKS9zVRdOi0eeJww== Date: Tue, 25 Feb 2025 19:20:55 +0100 From: Maxime Chevallier To: "Russell King (Oracle)" Cc: davem@davemloft.net, Andrew Lunn , Jakub Kicinski , Eric Dumazet , Paolo Abeni , Heiner Kallweit , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, thomas.petazzoni@bootlin.com, Florian Fainelli , =?UTF-8?B?S8O2cnk=?= Maincent , Simon Horman , Romain Gantois , Antoine Tenart , Marek =?UTF-8?B?QmVow7pu?= , Sean Anderson , =?UTF-8?B?QmrDuHJu?= Mork Subject: Re: [PATCH net-next v2 1/2] net: phy: sfp: Add support for SMBus module access Message-ID: <20250225192055.32168b48@fedora.home> In-Reply-To: References: <20250225112043.419189-1-maxime.chevallier@bootlin.com> <20250225112043.419189-2-maxime.chevallier@bootlin.com> Organization: Bootlin X-Mailer: Claws Mail 4.3.0 (GTK 3.24.43; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgdekvdegudcutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfitefpfffkpdcuggftfghnshhusghstghrihgsvgenuceurghilhhouhhtmecufedtudenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhepfffhvfevuffkjghfohfogggtgfesthejredtredtvdenucfhrhhomhepofgrgihimhgvucevhhgvvhgrlhhlihgvrhcuoehmrgigihhmvgdrtghhvghvrghllhhivghrsegsohhothhlihhnrdgtohhmqeenucggtffrrghtthgvrhhnpeegveeltddvveeuhefhvefhlefhkeevfedtgfeiudefffeiledttdfgfeeuhfeukeenucfkphepvdgrtddumegtsgduleemkegugegtmeelfhdttdemsggtvddumeekkeelleemheegtdgtmegvheelvgenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpedvrgdtudemtggsudelmeekugegtgemlehftddtmegstgdvudemkeekleelmeehgedttgemvgehlegvpdhhvghlohepfhgvughorhgrrdhhohhmvgdpmhgrihhlfhhrohhmpehmrgigihhmvgdrtghhvghvrghllhhivghrsegsohhothhlihhnrdgtohhmpdhnsggprhgtphhtthhopedukedprhgtphhtthhopehlihhnuhigsegrrhhmlhhinhhugidrohhrghdruhhkpdhrtghpthhtohepuggrvhgvmhesuggrvhgvmhhlohhfthdrnhgvthdprhgtphhtthhopegrnhgurhgvfieslhhunhhnrdgthhdprhgtphhtt hhopehkuhgsrgeskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepvgguuhhmrgiivghtsehgohhoghhlvgdrtghomhdprhgtphhtthhopehprggsvghnihesrhgvughhrghtrdgtohhmpdhrtghpthhtohephhhkrghllhifvghithdusehgmhgrihhlrdgtohhmpdhrtghpthhtohepnhgvthguvghvsehvghgvrhdrkhgvrhhnvghlrdhorhhg X-GND-Sasl: maxime.chevallier@bootlin.com On Tue, 25 Feb 2025 18:04:29 +0000 "Russell King (Oracle)" 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