linux-kernel - Re: [PATCH v9 07/12] dt-bindings: mfd: Add a document for PECI client MFD

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Date:   Wed, 2 Jan 2019 10:29:26 -0800
From:   Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>, Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Mark Rutland <mark.rutland@....com>,
        Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>,
        Jonathan Corbet <corbet@....net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Kishon Vijay Abraham I <kishon@...com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        Eric Sandeen <sandeen@...hat.com>,
        Arnd Bergmann <arnd@...db.de>, Wu Hao <hao.wu@...el.com>,
        Tomohiro Kusumi <kusumi.tomohiro@...il.com>,
        "Bryant G . Ly" <bryantly@...ux.vnet.ibm.com>,
        Frederic Barrat <fbarrat@...ux.vnet.ibm.com>,
        "David S . Miller" <davem@...emloft.net>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Vinod Koul <vkoul@...nel.org>,
        Stephen Boyd <sboyd@...eaurora.org>,
        David Kershner <david.kershner@...sys.com>,
        Uwe Kleine-Konig <u.kleine-koenig@...gutronix.de>,
        Sagar Dharia <sdharia@...eaurora.org>,
        Johan Hovold <johan@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Juergen Gross <jgross@...e.com>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>,
        linux-hwmon@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        openbmc@...ts.ozlabs.org,
        James Feist <james.feist@...ux.intel.com>,
        Jason M Biils <jason.m.bills@...ux.intel.com>,
        Vernon Mauery <vernon.mauery@...ux.intel.com>
Subject: Re: [PATCH v9 07/12] dt-bindings: mfd: Add a document for PECI client
 MFD

Hi Lee,

On 12/21/2018 6:47 AM, Lee Jones wrote:
> On Tue, 18 Dec 2018, Jae Hyun Yoo wrote:
> 
>> This commit adds a dt-bindings document for PECI client MFD.
>>
>> +* Intel PECI client bindings

<snip>

>> +PECI (Platform Environment Control Interface) is a one-wire bus interface that
>> +provides a communication channel from PECI clients in Intel processors and
>> +chipset components to external monitoring or control devices. PECI is designed
>> +to support the following sideband functions:
>> +
>> +- Processor and DRAM thermal management
>> +- Platform Manageability
>> +- Processor Interface Tuning and Diagnostics
>> +- Failure Analysis
>> +
>> +Required properties:
>> +- compatible : Should be "intel,peci-client".
>> +- reg        : Should contain address of a client CPU. According to the PECI
>> +	       specification, client addresses start from 0x30.
>> +
>> +Example:
>> +	peci-bus@0 {
>> +		compatible = "vendor,soc-peci";
>> +		reg = <0x0 0x1000>;
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +
>> +		peci-client@30 {
>> +			compatible = "intel,peci-client";
>> +			reg = <0x30>;
>> +		};
>> +
>> +		peci-client@31 {
>> +			compatible = "intel,peci-client";
>> +			reg = <0x31>;
>> +		};
> 
> The PECI Client driver (masquerading as an MFD driver in this set)
> doesn't actually do anything special.  Instead of detailing it here,
> register the child devices directly instead.
> 

Main purpose of the PECI client driver is providing 'reg' value to its
child devices. If I add the child nodes directly, compiler will make
warnings while building dtb because the child nodes are using the same
unit address.

Thanks,
Jae