On 09/14/2012 08:30 AM, Domenico Andreoli wrote: > On Fri, Sep 14, 2012 at 03:48:05PM +0200, Linus Walleij wrote: >> On Fri, Sep 14, 2012 at 12:11 AM, Domenico Andreoli <cav...@gmail.com> wrote: >>> On Thu, Sep 13, 2012 at 10:11:29AM -0600, Stephen Warren wrote: >> >>>> I think it makes sense to more strongly recommend that for GPIO muxing, >>>> the GPIO driver always call into the pinctrl subsystem (if needed by the >>>> HW) to perform that muxing, so that standalone gpio_direction_*() always >>>> work without any use of pinctrl; the interaction between the two should >>>> only be required if pin configuration (not just pin muxing) is also >>>> required. >>> >>> Don't know. Isn't possible to reach the same effect moving this kind >>> of knowledge into higher level helper functions and remove this bridge >>> across the subsystems? >> >> I'm not following, please elaborate on this. >> >> What are these higher level functions, and where will they be >> located? In which subsystem, and using what symbols/signatures and >> so on? > > If the common case is requesting the pin and then the gpio, an helper > like this would do the trick. So why those calls into pinctrl should be > done by the GPIO driver itself? Pinctrl and GPIO would be separated, > ignoring each other. > > static int request_muxed_gpio(int gpio, const char *label)
That would require the driver to know when to call gpio_request() as opposed to request_muxed_gpio() wouldn't it. Whether that is needed or not depends on the Soc/board the driver is running on. The whole idea of the internal GPIO->pinctrl driver communication was to avoid that. I suppose that if we were to mandate that ever device that uses GPIOs also have at least some (possibly empty) pinctrl state defined, then request_muxed_gpio() could always be used. However, that's quite a strong requirement. An also, if we were to make that rule, then we might as well just implement this inside the existing gpio_request(), so that no driver changes were required. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
