linux-kernel - Re: [PATCH v2 2/5] Power: reset: add bindings for keystone reset driver

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Date:	Tue, 15 Apr 2014 14:25:13 +0300
From:	Ivan Khoronzhuk <ivan.khoronzhuk@...com>
To:	Arnd Bergmann <arnd@...db.de>,
	<linux-arm-kernel@...ts.infradead.org>
CC:	<dbaryshkov@...il.com>, <dwmw2@...radead.org>,
	<robh+dt@...nel.org>, <pawel.moll@....com>, <mark.rutland@....com>,
	<ijc+devicetree@...lion.org.uk>, <galak@...eaurora.org>,
	<santosh.shilimkar@...com>, <grant.likely@...aro.org>,
	<devicetree@...r.kernel.org>, <grygorii.strashko@...com>,
	<linux@....linux.org.uk>, <linux-doc@...r.kernel.org>,
	<w-kwok2@...com>, <rdunlap@...radead.org>, <sboyd@...eaurora.org>,
	<linux-kernel@...r.kernel.org>, <olof@...om.net>
Subject: Re: [PATCH v2 2/5] Power: reset: add bindings for keystone reset
 driver


On 04/14/2014 09:44 PM, Arnd Bergmann wrote:
> On Monday 14 April 2014 20:41:20 Ivan Khoronzhuk wrote:
>> +Optional properties:
>> +
>> +- ti,soft-reset:       Boolean option indicating soft reset.
>> +                       By default hard reset is used.
>> +
>> +- ti,wdt_list:         WDT list that can cause SoC reset.
>> +                       The list in format: <0>, <2>;
>> +                       Begins from 0 to 3, as keystone can contain up
>> +                       to 4 SoC reset watchdogs.
>>
> This looks like your binding just describes a subset of the
> watchdog timer registers. If so, don't do a standalone reset

The registers are not a subset of watchdog hardware it's SoC specific future
controlled by SoC specific registers (bootregs and PLL regs).

For watchog IP setup, the Keystone uses the watchdog driver common with 
other
SoCs -- davinci_watchdog that is not depend on other SoC settings like 
this driver does.

The Keystone SoCs have separate registers to tune Keystone2 reset 
functionality
by configuring Reset multiplexer &  PLL. And it tunes not only watchdog 
usage.
The keystone SoC can be rebooted in several ways. By external reset pin, 
by soft and
by watchdogs. This driver allows software reset or reset by one of the 
watchdogs
(and other settings) independently on watchdog driver settings. This is 
job of reset driver.

> It's
> driver, but instead do a watchdog driver that can also be
> used for reset, and have a binding that properly describes
> the watchdog hardware.
>
> It is bad to have overlapping register ranges between logical

WDT doesn't overlap with this driver.

> devices, and it's also generally wrong to describe devices that
> are not actually there: The hardware contains a watchdog, not
> a system-reset device, so you should not make one up because
> it seems easier given the Linux driver model.
>
> 	Arnd



-- 
Regards,
Ivan Khoronzhuk

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