linux-kernel - Re: [PATCH 5/6] pinctrl: tegra: Add DT binding for io pads control

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Message-ID: <57289F88.6040203@nvidia.com>
Date:	Tue, 3 May 2016 18:24:32 +0530
From:	Laxman Dewangan <ldewangan@...dia.com>
To:	Jon Hunter <jonathanh@...dia.com>, <swarren@...dotorg.org>,
	<linus.walleij@...aro.org>, <gnurou@...il.com>,
	<robh+dt@...nel.org>, <mark.rutland@....com>,
	<thierry.reding@...il.com>
CC:	<linux-tegra@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH 5/6] pinctrl: tegra: Add DT binding for io pads control


On Tuesday 03 May 2016 06:14 PM, Jon Hunter wrote:
> On 02/05/16 13:17, Laxman Dewangan wrote:
>> +
>> +The voltage supported on the pads are 1.8V and 3.3V. The enums are defined as:
>> +	For 1.8V, use TEGRA_IO_PAD_POWER_SOURCE_1800000UV
>> +	For 3.3V, use TEGRA_IO_PAD_POWER_SOURCE_3300000UV
> Are these still necessary now that the driver is using uV? Can't we just
> use integer values for 1800000 and 3300000 in the DTS directly?
>
The config param and value are packed in u32 with 16bit each So we can 
not make uV in 16bit until we do conversion of uV->mV.
Hence suggestion came from Stephen that we can have enum for Nvidia 
specific and what actually it supports by HW. HW does not support any 
other voltage.


>> +Required subnode-properties:
>> +==========================
>> +- pins : An array of strings. Each string contains the name of an IO pads. Valid
>> +	 values for these names are listed below.
> Please see my previous comments.

This is taken from other dt binding docs for description. We can have 
array of string.
As all value of pins are not supporting all property and hence I 
explicitly wrote under properties.

>
>> +Optional subnode-properties:
>> +==========================
>> +-nvidia,power-source-voltage:	Integer. The voltage level of IO pads. The
> I think I prefer nvidia,io-voltage or something. You can describe what
> this means in this doc. In fact, the current description here does not
> explicitly state that this voltage, is the voltage the pad is configured
> to operate at versus the voltage of the IO rail.

Linus suggested this dt property name to make more readable and generic 
and meaningful with other property :power-source.