Re: [patch/rfc 2.6.19-rc5] arch-neutral GPIO calls

["H. Peter Anvin" <hpa@zytor.com>]

David Brownell wrote:
>   - Only intended for use with "real" GPIOs that work from IRQ context;
>     e.g. pins on a SOC that are controlled by chip register access.
>
>   - Doesn't handle I2C or SPI based GPIOs.  I think we actually need
>     a different API for those "message based" GPIOs, where synchronous
>     get/set requires sleeping (and is thus unusable from IRQ context).
>     That API could be used for "real" GPIOs; the converse is not true.
>
>   - No IORESOURCE_GPIO resource type (could be added though).
>
>   - Can be trivially implemented today, on many systems (see partial
>     list above) ... no "provider" or gpiochip API necessary.
>
>   - Provided in the form of a working patch, with sample implementation;
>     known to be viable on multiple architectures and platforms.
>
>   - Includes Documentation/gpio.txt
>
> Comments?

If this is done, I think it's essential that a "high-level" API (one 
that supports message-based GPIO) is provided at the same time.  The 
"high-level" API should be able to address the GPIOs addressed by the 
low-level API.  What we do *not* want is a bunch of stuff using the 
low-level API when the high-level API would work.

	-hpa
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