linux-kernel - Re: [PATCH RFC 1/2] gpio: Add a block GPIO API to gpiolib

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Message-ID: <5068204F.6090606@antcom.de>
Date:	Sun, 30 Sep 2012 12:34:55 +0200
From:	Roland Stigge <stigge@...com.de>
To:	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
CC:	linus.walleij@...aro.org, linux-kernel@...r.kernel.org,
	w.sang@...gutronix.de, grant.likely@...retlab.ca,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH RFC 1/2] gpio: Add a block GPIO API to gpiolib

On 29/09/12 21:57, Jean-Christophe PLAGNIOL-VILLARD wrote:
>> Problem here is that it's only an intermediate format since hardware
>> often needs special preparation of the data.
>>
>> But will evaluate what makes most sense.
> the key point here is to avoid to manipualte data each time we call
> gpio_block_set
> 
> hardware specific will have to be handle at driver level

Understand, thanks! I'm just trying to prevent overly complex API because:

* In our discussed scheme, the driver still needs to convert the data bits
* In practice, the block gpio API is especially useful for use on single
gpio_chips (only there, a real simultaneous i/o is possible anyway)
* Wouldn't introduce this kind of optimization in lack of measurable
improvement
* The actual i/o data bits still need handling, generating a bit CPU
load anyway.

Trying to provide as simple API as possible.

Roland
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