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[2003:ea:8f20:6900:9d47:8de1:7320:72f5]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-477bf3af0e1sm26049155e9.10.2025.11.20.22.53.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 20 Nov 2025 22:53:22 -0800 (PST) Message-ID: <8cbd4650-aeed-4d1c-8173-957776dfec51@gmail.com> Date: Fri, 21 Nov 2025 07:53:21 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Question] Return value of mii_bus->write() To: Buday Csaba , netdev@vger.kernel.org References: Content-Language: en-US From: Heiner Kallweit In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/21/2025 7:31 AM, Buday Csaba wrote: > I am preparing a patch to eliminate kernel-doc warnings in mdio_device.c > and mdio_bus.c > > I have ran into an ambiguity: what is mii_bus->write() supposed to > return on success? Documentation/networking/phy.txt does not give any > information about it, neither does the kdoc in include/linux/phy.h. > > It is clear that 0 is treated as success, and a negative indicates > failure. The reference implementation also follows this convention. > But the code in mdio_bus.c, for example: __mdiobus_modify_changed(), > seems to also expect positive return values from write(). > I think you misread the code. __mdiobus_modify_changed() returns a positive value in case new and old value differ, but __mdiobus_write() never returns a positive value. > Is there any other implementation that allows positive return > values for success? Should it be mentioned in kernel-doc? > > Thanks, > Csaba > >