linux-kernel - RE: [PATCH 1/2] dt-bindings: trivial-devices: add lt3074

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Message-ID:
 <PH0PR03MB693845F71D14B21D447D701A8EFB2@PH0PR03MB6938.namprd03.prod.outlook.com>
Date: Mon, 17 Feb 2025 09:30:26 +0000
From: "Encarnacion, Cedric justine" <Cedricjustine.Encarnacion@...log.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
CC: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>, Jean Delvare <jdelvare@...e.com>,
        Guenter
 Roeck <linux@...ck-us.net>, Jonathan Corbet <corbet@....net>,
        Delphine CC
 Chiu <Delphine_CC_Chiu@...ynn.com>,
        "devicetree@...r.kernel.org"
	<devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>,
        "linux-hwmon@...r.kernel.org"
	<linux-hwmon@...r.kernel.org>,
        "linux-doc@...r.kernel.org"
	<linux-doc@...r.kernel.org>,
        "linux-i2c@...r.kernel.org"
	<linux-i2c@...r.kernel.org>
Subject: RE: [PATCH 1/2] dt-bindings: trivial-devices: add lt3074

> On 06/02/2025 10:05, Encarnacion, Cedric justine wrote:
> >> -----Original Message-----
> >> From: Krzysztof Kozlowski <krzk@...nel.org>
> >> Sent: Monday, January 27, 2025 3:52 PM
> >> To: Encarnacion, Cedric justine <Cedricjustine.Encarnacion@...log.com>
> >> Cc: Rob Herring <robh@...nel.org>; Krzysztof Kozlowski
> <krzk+dt@...nel.org>;
> >> Conor Dooley <conor+dt@...nel.org>; Jean Delvare
> <jdelvare@...e.com>;
> >> Guenter Roeck <linux@...ck-us.net>; Jonathan Corbet <corbet@....net>;
> >> Delphine CC Chiu <Delphine_CC_Chiu@...ynn.com>;
> >> devicetree@...r.kernel.org; linux-kernel@...r.kernel.org; linux-
> >> hwmon@...r.kernel.org; linux-doc@...r.kernel.org; linux-
> i2c@...r.kernel.org
> >> Subject: Re: [PATCH 1/2] dt-bindings: trivial-devices: add lt3074
> >>
> >> [External]
> >>
> >> On Fri, Jan 24, 2025 at 11:39:06PM +0800, Cedric Encarnacion wrote:
> >>> Add Analog Devices LT3074 Ultralow Noise, High PSRR Dropout Linear
> >>> Regulator.
> >>
> >> Regulator? Then why is it trivial? No enable-gpios? No I2C interface?
> >>
> >> Best regards,
> >> Krzysztof
> >
> > I based this driver primarily on the LT7182S dual-channel silent switcher
> > regulator.
> 
> 
> I do not understand why the base of driver matters here? If it was based
> on LTFOOBARGROUNDHOG1 would it change something? I know neither
> LT7182S
> nor the LTFOOBARGROUNDHOG1. And driver matters here even less -
> bindings
> are about hardware, not given implementation in OS.
> 
> > The LT3074 is a single-channel device with basic enable and
> > power-good GPIOs, fewer registers, and fewer functionalities than the
> 
> So it has GPIOs? And by GPIOs you mean what the SoC/CPU, thus the
> operating system, sees as GPIOs or something else?

Yes, the OS sees these as GPIOs.

> 
> > LT7182S. Like other PMBus drivers, its GPIOs are not exposed.
> >
> > Here are other PMBus regulators/power modules found in trivial-devices
> > I also used as reference:
> >
> > - infineon,irps5401
> > - delta,q54sj108a2
> 
> 
> I don't know these devices so still no clue. Please rather explain in
> the terms of the hardware, e.g. what this device has or has not. See
> also regulator bindings.

The device has enable-gpio and status-gpio. It also has registers of
similar functionality which the core driver accesses instead for
toggling enable and monitoring status of the device.

Upon checking regulator bindings and other related bindings for
PMBus devices with regulator support, this indeed should be a
separate binding outside of trivial devices. Please let me know
what do you suggest.

Best Regards,
Cedric