From: Rob Herring <robh@kernel.org>
To: Michael Shych <michaelsh@nvidia.com>
Cc: "linux@roeck-us.net" <linux@roeck-us.net>,
"linux-hwmon@vger.kernel.org" <linux-hwmon@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
Vadim Pasternak <vadimp@nvidia.com>
Subject: Re: [PATCH hwmon-next v4 2/3] dt-bindings: hwmon: add Microchip EMC2305 fan controller.
Date: Thu, 4 Aug 2022 11:45:48 -0600 [thread overview]
Message-ID: <20220804174548.GB4145453-robh@kernel.org> (raw)
In-Reply-To: <DM6PR12MB40747C492C3197BDD64027FCD48C9@DM6PR12MB4074.namprd12.prod.outlook.com>
On Mon, Jul 18, 2022 at 12:38:58PM +0000, Michael Shych wrote:
> Hi,
>
> Sorry for long delay in getting back to you.
> Please see below.
>
> Thanks,
> Michael.
>
> > -----Original Message-----
> > From: Rob Herring <robh@kernel.org>
> > Sent: Friday, July 1, 2022 1:12 AM
> > To: Michael Shych <michaelsh@nvidia.com>
> > Cc: linux@roeck-us.net; linux-hwmon@vger.kernel.org;
> > devicetree@vger.kernel.org; Vadim Pasternak <vadimp@nvidia.com>
> > Subject: Re: [PATCH hwmon-next v4 2/3] dt-bindings: hwmon: add Microchip
> > EMC2305 fan controller.
> >
> > On Thu, Jun 23, 2022 at 07:52:16PM +0300, michaelsh@nvidia.com wrote:
> > > From: Michael Shych <michaelsh@nvidia.com>
> > >
> > > Add basic description of emc2305 driver device tree binding.
> > >
> > > Signed-off-by: Michael Shych <michaelsh@nvidia.com>
> > > Reviewed-by: Vadim Pasternak <vadimp@nvidia.com>
> > > ---
> > > v2->v3
> > > Changes pointed out by Rob Herring and Guenter Roeck:
> > > - Describe separate channels of fan-controller;
> > > - Remove pwm_max property;
> > > - Fix compatible property.
> > > Changes added by Michael Shych:
> > > - Fix dt binding check warnings.
> > > v1->v2
> > > - Fix dt binding check errors;
> > > - Add descriptions;
> > > - Add missing fields;
> > > - Change the patch subject name;
> > > - Separate pwm-min, pwm-max per PWM channel.
> > > ---
> > > .../bindings/hwmon/microchip,emc2305.yaml | 106
> > +++++++++++++++++++++
> > > 1 file changed, 106 insertions(+)
> > > create mode 100644
> > > Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> > >
> > > diff --git
> > > a/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> > > b/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> > > new file mode 100644
> > > index 000000000000..d054ba46ae23
> > > --- /dev/null
> > > +++
> > b/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> > > @@ -0,0 +1,106 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) %YAML 1.2
> > > +---
> > > +
> > > +$id: http://devicetree.org/schemas/hwmon/microchip,emc2305.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Microchip EMC2305 RPM-based PWM Fan Speed Controller
> >
> > RPM-based? So there is a tach signal too? Don't those need the number of
> > pulses per revolution that the fan provides.
> >
> It's not relevant. The driver implements Direct setting mode according
> to the Datasheet: https://www.microchip.com/en-us/product/EMC2305
> I can add this note to the documentation patch.
For the binding, it doesn't matter what a driver currently implements.
That's one driver at one point in time. Bindings shouldn't be evolving
and need to support more than 1 OS.
The binding needs to be able to describe the h/w. If there's a tach
connection, you need to describe that and the properties of the fan's
tach pulses.
>
> > To repeat what I say for every fan controller binding now, until there's a
> > common binding to describe fan controllers, fans and their relationship to
> > each other, I'm not signing off on any fan binding doing its own thing.
> >
> I'm confused here as I thought that I already changed to common fan-controller with advice of
> Gunter in patch series V3.
> Do you mean that we should use some common FAN/PWM/ TACHO etc. generic binding
> mechanism that fits all drivers?
> Could you advise if it's already existed and reference to example?
It doesn't exist. Probably the closest binding to something as a basis
for something common is npcm750-pwm-fan.txt.
> If it doesn't exist, it'll be too complicated to provide such a new generic description within
> the submission of a driver for EMC2305 device.
> We can just completely remove OF interface and pass the necessary configuration through
> the platform data.
That's your choice...
Rob
next prev parent reply other threads:[~2022-08-04 17:45 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-23 16:52 [PATCH hwmon-next v4 0/3] Add support for EMC2305 Fan Speed Controller michaelsh
2022-06-23 16:52 ` [PATCH hwmon-next v4 1/3] hwmon: (emc2305) add support for EMC2301/2/3/5 RPM-based PWM " michaelsh
2022-06-23 16:52 ` [PATCH hwmon-next v4 2/3] dt-bindings: hwmon: add Microchip EMC2305 fan controller michaelsh
2022-06-30 22:11 ` Rob Herring
2022-07-18 12:38 ` Michael Shych
2022-08-04 17:45 ` Rob Herring [this message]
2022-06-23 16:52 ` [PATCH hwmon-next v4 3/3] docs: hwmon: add emc2305.rst to docs michaelsh
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