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Sender: Guenter Roeck <groeck7@gmail.com>
Date: Tue, 2 Apr 2024 15:17:32 -0700
From: Guenter Roeck <linux@roeck-us.net>
To: Chris Packham <Chris.Packham@alliedtelesis.co.nz>
Cc: "jdelvare@suse.com" <jdelvare@suse.com>,
	"linux-hwmon@vger.kernel.org" <linux-hwmon@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: hwmon: label vs temp%d_label
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In-Reply-To: <9f58389e-0eb6-4ff1-9152-aa38dbfc5f8b@alliedtelesis.co.nz>

On Tue, Apr 02, 2024 at 09:57:44PM +0000, Chris Packham wrote:
> 
> On 3/04/24 10:22, Chris Packham wrote:
> >
> > On 3/04/24 09:59, Guenter Roeck wrote:
> >> On Tue, Apr 02, 2024 at 08:24:37PM +0000, Chris Packham wrote:
> >>> Hi Guenter, Jean,
> >>>
> >>> I've got a requirement to add some meaningful names to some hwmon
> >>> sensors (LM75 specifically) so that we can provide some indication of
> >>> where on a board the sensor is located (e.g. "Intake" vs "Exhaust" vs
> >>> "Near that really hot chip").
> >>>
> >>> I see that the sysfs ABI documents both "label" for the chip and
> >>> "temp[1-*]_label" (as well as similar fan and Vin attributes). The
> >>> latter seem to be supported by the hwmon core but I don't see anything
> >>> for the former (I'm struggling to find any driver that supports a
> >>> chip-wide label).
> >>>
> >>> Assuming I want to have a label added in the device tree to a lm75 
> >>> would
> >>> something like the following be acceptable
> >>>
> >>> ? ????? sensor@48 {
> >>> ? ??????? compatible = "national,lm75";
> >>> ? ??????? reg = <0x48>;
> >>> ? ??????? label = "Intake";
> >>> ? ????? };
> >>>
> >>> I'd then update the lm75 driver to grab that from the devicetree and 
> >>> use
> >>> it to provide the hwmon_temp_label attribute.
> >>>
> >> Have you tried just declaring the label property as you suggested above
> >> in your system without doing anything else, and looked at the generated
> >> sysfs attributes ?
> >
> > I have not. But in my defense I'm also using an older kernel LTS that 
> > doesn't have commit e1c9d6d61ddf ("hwmon: Add "label" attribute"). But 
> > now that I know it exists I can carry it as a local patch until we 
> > next update.
> 
> Related is there an lm-sensors change that uses this attribute for 
> display purposes?
> 
Sorry, I don't know. I stopped paying attention to the lm-sensors package
a long time ago, and I don't know its status. I just don't have the time.

> I do have a couple of PRs open on the lm-sensors github project I'd like 
> to see merged but given recent events this should absolutely not be 
> construed as a criticism of anyone maintaining lm-sensors merely a query 
> as to whether PRs are the right path for changes or if they should be 
> sent to a mailing list somewhere.
> 
I have no idea, sorry.

Guenter