linux-kernel - Re: [PATCH v2] dt-bindings: trivial-devices: add onnn,adt7462

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Message-ID: <20240924-cringe-puma-67798ccadc66@spud>
Date: Tue, 24 Sep 2024 09:20:15 +0100
From: Conor Dooley <conor@...nel.org>
To: Guenter Roeck <linux@...ck-us.net>
Cc: Chanh Nguyen <chanh@...eremail.onmicrosoft.com>,
	Chanh Nguyen <chanh@...amperecomputing.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Peter Yin <peteryin.openbmc@...il.com>,
	Noah Wang <noahwang.wang@...look.com>, Marek Vasut <marex@...x.de>,
	Fabio Estevam <festevam@...il.com>, Lukas Wunner <lukas@...ner.de>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
	Phong Vo <phong@...amperecomputing.com>,
	Thang Nguyen <thang@...amperecomputing.com>,
	Quan Nguyen <quan@...amperecomputing.com>,
	Khanh Pham <khpham@...erecomputing.com>,
	Open Source Submission <patches@...erecomputing.com>
Subject: Re: [PATCH v2] dt-bindings: trivial-devices: add onnn,adt7462

On Mon, Sep 23, 2024 at 10:39:20PM -0700, Guenter Roeck wrote:
> On 9/23/24 21:17, Chanh Nguyen wrote:
> > On 24/09/2024 04:23, Conor Dooley wrote:
> > > On Mon, Sep 23, 2024 at 09:38:00AM +0000, Chanh Nguyen wrote:
> > > > The adt7462 supports monitoring and controlling up to
> > > > four PWM Fan drive outputs and eight TACH inputs measures.
> > > > The adt7462 supports reading a single on chip temperature
> > > > sensor and three remote temperature sensors. There are up
> > > > to 13 voltage monitoring inputs.
> > > > 
> > > > Add device tree bindings for the adt7462 device.
> > > > 
> > > > Signed-off-by: Chanh Nguyen <chanh@...amperecomputing.com>
> > > > ---
> > > > Change in v2:
> > > >     - Add onnn,adt7462 to the list of trivial devices       [Guenter]
> > > 
> > > Is this really a trivial device? If it monitors and controls fans, how
> > > come those do not need to be represented in the devicetree? How is it
> > > possible to tell the difference between monitoring 1 and 4 fans without
> > > the extra detail?
> > > 
> > 
> > Hi Conor, Thank you for your comments!
> > 
> > The chip is old. The driver was added back in 2008.
> > 
> > Really, this is such an old chip that it would make more sense to just leave its driver alone unless there is a problem with it; this is viewpoint from Guenter.
> > 
> > I'm using the driver and the device tree with only the "compatible" and "reg" properties; now it's being good for me without any extra detail.
> > 
> > Guenter, Rob, Krzysztof, and I discussed making the decision to add this device to the list of trivial devices. You can get more information at thread https://lore.kernel.org/lkml/20240918220553.GA2216504-robh@kernel.org/T/ (Because the commit title changed between v1 and v2, it's so hard for everyone to find it. Sorry! I missed mentioning the link to pacth v1).
> > 
> > Guenter, who supported the driver development before, he suggested me add this device to the list of trivial devices.
> > 
> 
> Historically it was ok to add an entry into trivial devices and extending
> it later if/when needed. That was still widely done at least until very
> recently. Maybe that changed recently. If so, sorry for bringing up the idea.
> I did not envision that this might be a problem.
> 
> Can you live with no devicetree entry at all for the chip ? That is of
> course less than perfect, but it seems better than trying to design a
> devicetree description for the chip only to never implement it.

Since it sounds like Krzysztof assented to it, I'll just leave it for
him to ack.

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