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Sun, 22 Mar 2026 11:18:49 +0100 Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Sun, 22 Mar 2026 11:18:49 +0100 Message-Id: Cc: , Subject: Re: Weird Dell SMM bug since 6.18 From: "Guy Boldon" To: "Guenter Roeck" , "Guy Boldon" , X-Mailer: aerc 0.21.0 References: <97b6c751-0115-4d00-b212-352f37e5914d@roeck-us.net> <02d1330f-1439-4291-bbb2-289122eedd7c@roeck-us.net> <62d86acf-6a3f-4bb2-9d81-cf47bd1461e9@roeck-us.net> <20260319094944.239871-1-gb@guyboldon.com> In-Reply-To: X-AuthUser: gb@guyboldon.com Hi Guenter, Thank you for the explanations, much appreciated.=20 On Thu Mar 19, 2026 at 4:52 PM CET, Guenter Roeck wrote: > The use of -ENODATA in hwmon to report that a value is not available is > relatively new and isn't even fully documented in the sysfs ABI (admitted= ly > a major oversight). The major driver for its use is that it more accurate= ly > reflects reality as reported by the "sensors" command if an attribute val= ue > is not available (sensors reports "N/A" instead of an error message if it > gets an -ENODATA error). Ah, it seemed somewhat new and that makes sense. -ENODATA converts to a clean N/A without an error message. We will adjust to handle -ENODATA=20 going forward. >> As a related point: gpd_fan returns -EOPNOTSUPP rather than -ENODATA >> when in auto mode, and documents that behavior in the kernel docs. The > > Please feel free to submit a patch to fix that. I'll submit a patch for that. > The best we can do is to find a means to improve consistency, but as you > can see here even that is difficult because different people will have > different opinions on how that consistency should look like. Error respon= se > will vary, as will attribute visibility. > > If you would like to get actively involved, please feel free to submit pa= tches > improving the documentation (Documentation/hwmon/sysfs-interface.rst, > Documentation/ABI/testing/sysfs-class-hwmon, and or driver specific > documentation) as well as driver patches to help improve consistency acro= ss > drivers. I agree and I would like to help improve consistency for the interface. I'l= l look at the docs as well. CoolerControl is a direct consumer of this interf= ace across a large range of drivers, but improving consistency, I think, benefi= ts=20 anyone interacting with more than a handful of drivers. Thanks again, Guy