On Thu, 15 Nov 2007 00:20:33 -0800 David Brownell <[EMAIL PROTECTED]> wrote:
> > > - gpio_direction_input()/gpio_direction_output() implicitly > > > request the pins, if they weren't already requested. > > > > Eek, that's completely wrong. Allowing to access a resource _before_ > > it is assigned and then doing the assignment implicit is a really bad > > idea. > > This is an artifact of making the GPIO interface easy to adopt, > by letting all the initial adopters wrap "legacy" SOC-specific > GPIO interfaces instead of creating a bunch of new platform code. It's still ok for platforms that do not use gpiolib to provide NOP gpio_request() and gpio_free() functions if they don't care about tracking gpio usage. That doesn't mean we shouldn't require all drivers to use those calls -- if they are implemented as empty inlines, it won't cost anything to call them. I'd rather speed up the gpio_direction_* functions a bit by removing the implicit gpio_request() since they may be called a lot more frequently and, as you pointed out, possibly from atomic context. Håvard - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
