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([2001:9e8:f13f:1001:fd79:63dc:69b7:40d3]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b87959c9bc9sm230975466b.33.2026.01.16.05.43.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 16 Jan 2026 05:43:48 -0800 (PST) Message-ID: <6987689b-35ac-4c15-addb-1c8e54144fa7@gmail.com> Date: Fri, 16 Jan 2026 14:43:47 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v5] net: sfp: extend SMBus support Content-Language: en-US To: Maxime Chevallier , Russell King , Andrew Lunn , Heiner Kallweit , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, =?UTF-8?Q?Bj=C3=B8rn_Mork?= References: <20260116113105.244592-1-jelonek.jonas@gmail.com> <6a87648c-a1e8-49a2-a201-91108669ab44@bootlin.com> From: Jonas Jelonek In-Reply-To: <6a87648c-a1e8-49a2-a201-91108669ab44@bootlin.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, On 16.01.26 14:23, Maxime Chevallier wrote: > I think Russell pointed it out, but I was also wondering the same. > How do we deal with controllers that cannot do neither block nor > single-byte, i.e. that can only do word access ? > > We can't do transfers that have an odd length. And there are some, > see sfp_cotsworks_fixup_check() for example. > > Maybe these smbus controller don't even exist, but I think we should > anyway have some log saying that this doesn't work, either at SFP > access time, or at init time. I tried to guard that in the sfp_i2c_configure() right now. The whole path to allow SMBus transfers is only allowed if there's at least byte access. For exactly the reason that we need byte access in case of odd lengths. Then, it can upgrade to word or block access if available. Or did I miss anything in the conditions? This of course rules out any controllers which just can do word access. I guess covering this case increases the complexity. But I'd be fine having a log or something similar handling this condition. Kind regards, Jonas