linux-kernel - Re: [PATCH 1/2] gpio/gpio-generic: read set register for caching if available

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Message-ID: <4E11E2DC.2070601@linutronix.de>
Date:	Mon, 04 Jul 2011 17:57:16 +0200
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	Grant Likely <grant.likely@...retlab.ca>
CC:	linux-kernel@...r.kernel.org, sodaville@...utronix.de
Subject: Re: [PATCH 1/2] gpio/gpio-generic: read set register for caching
 if available

Grant Likely wrote:
>> diff --git a/drivers/gpio/gpio-generic.c b/drivers/gpio/gpio-generic.c
>> index 231714d..9f8b5c6 100644
>> --- a/drivers/gpio/gpio-generic.c
>> +++ b/drivers/gpio/gpio-generic.c
>> @@ -398,7 +398,10 @@ int __devinit bgpio_init(struct bgpio_chip *bgc,
>>  	if (ret)
>>  		return ret;
>>  
>> -	bgc->data = bgc->read_reg(bgc->reg_dat);
>> +	if (bgc->reg_set)
>> +		bgc->data = bgc->read_reg(bgc->reg_set);
> 
> On most of the gpio controllers that I've seen, the 'set' register
> isn't something that you can actually read.  I don't think this is
> something that can be done for all gpio controllers.

I see. So

	if (bgc->reg_set && ! bgc->reg_clr)

instead should be fine, right?

> g.
> 
Sebastian
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