linux-kernel - Re: [PATCH v1 1/1] gpio: of: provide option generic property for initial line states

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Message-ID: <2432df7e-5d20-42c9-ddc0-044c2ca5ce2b@mentor.com>
Date:   Sun, 11 Jun 2017 22:57:18 +0300
From:   Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
To:     Oleksij Rempel <ore@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>
CC:     Oleksij Rempel <o.rempel@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Alexandre Courbot <gnurou@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        <barebox@...ts.infradead.org>
Subject: Re: [PATCH v1 1/1] gpio: of: provide option generic property for
 initial line states

Hi Oleksij,

On 06/11/2017 09:19 AM, Oleksij Rempel wrote:
> Hi Rob,
> 
> On Fri, Jun 09, 2017 at 10:41:30AM -0500, Rob Herring wrote:
>> On Fri, Jun 9, 2017 at 9:16 AM, Oleksij Rempel <o.rempel@...gutronix.de> wrote:
>>> This property is needed for barebox or may be other bootloaders
>>> to set proper gpio configuration as early as possible.
>>>
>>> This example is mainly based on "lines-initial-states" property
>>> from this binding documentation:
>>> Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt
>>
>> Don't we have a binding for this already based on gpio-hogs.
> 
> Markus Pargmann was working on this topic before and suddenly was not
> able to finish it.

that's fine, but the proposed extension is supposedly not wanted.

> I found only some not finished discussions and no code or documentation
> in linux kernel upstream.
> 
> So far, I was able to find fallowing patches and discussions:
> patch 23.08.2015, last comment 11.05.2017:
> https://patchwork.kernel.org/patch/7096721/
> 
> patch 23.02.2016, last comment 09.03.2016:
> https://patchwork.ozlabs.org/patch/586743/
> 
> Since there was objections about node-like design for gpio-initval, I
> provided an array property, which is similar to initval properties already used
> for different other device nodes. For example:
> 
> Documentation/devicetree/bindings/net/wireless/qcom,ath10k.txt
> qcom,ath10k-calibration-data
> 
> Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt
> lines-initial-states

It'd rather be better to fix the drivers and remove the properties
from these found device tree binding descriptions.

> 
> Please fixme if I miss something.

Why is GPIO hogging mechanism not good enough for your purpose?

--
With best wishes,
Vladimir