linux-kernel - Re: [PATCH 1/4] mfd: ab8500: add devicetree support for fuelgauge

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Message-ID: <50A4D362.5060402@stericsson.com>
Date:	Thu, 15 Nov 2012 17:04:58 +0530
From:	Rajanikanth HV <rajanikanth.hv@...ricsson.com>
To:	Francesco Lavra <francescolavra.fl@...il.com>
Cc:	Rajanikanth H V <rajanikanth.hv@...aro.org>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	"lee.jones@...aro.org" <lee.jones@...aro.org>,
	"arnd@...db.de" <arnd@...db.de>,
	"anton.vorontsov@...aro.org" <anton.vorontsov@...aro.org>,
	Linus WALLEIJ <linus.walleij@...ricsson.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-dev@...ts.linaro.org" <linaro-dev@...ts.linaro.org>,
	"patches@...aro.org" <patches@...aro.org>,
	STEricsson_nomadik_linux <STEricsson_nomadik_linux@...t.st.com>
Subject: Re: [PATCH 1/4] mfd: ab8500: add devicetree support for fuelgauge



On Saturday 10 November 2012 10:23 PM, Francesco Lavra wrote:
>>> I don't get the point of declaring the char array and copying the string
>>> in it, when you could simply use just the pointer returned by
>>> of_get_property().
>>
>> I am considering a corner case where in 'battery-type' property is not
>> present and battery is connected.In this case i promote battery to
>> UNKNOWN from null.
> 
> You could achieve the same result without using the char array, with
> this assignment:
> 
> btech = "UNKNOWN";
> 
>> FYI: Further, btemp driver will identify the connected battery based on
>> resistance value and decide to use.
>> Ref: ab8500_btemp_id(...) ab8500_btemp.c
>>
>>> Anyway, if the string property is longer than 8 characters, you are
>>> writing past the size of the destination array.
>>
>> i believe it is safe as power_supply.h comprises defines having battery
>> technology type in 4 characters length which is normally the case and
>> 7 chars length being "UNKNOWN" seldom referred
> 
> You should be able to handle whatever the device tree contains, and if
> it contains unexpected data this is not a good excuse for locking up the
> system.
agreed, if we were to go by what device tree contains then explicit
assignment for battery type as "UNKNOWN" is not required, hence only 2
use case persist as :
a) property name with one of the said value be present
	(as per documentation)
b) property name not present
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