On Fri, Sep 14, 2012 at 7:16 PM, Stephen Warren <swar...@wwwdotorg.org> wrote: > On 09/14/2012 07:49 AM, Linus Walleij wrote:
>> +If a pin control driver and a GPIO driver is dealing with the same pins >> +and the use cases involve multiplexing, you MUST implement the pin >> controller >> +as a back-end for the GPIO driver like this. > > I might add one caveat to that: > > ========== > , unless your HW design is such that the GPIO controller can override > the pin controller's mux state, without the need for any such interaction. > ========== OK I buy that, so added this paragraph (slightly rephrased) and pused for next. > In the future, I wonder if someone might want the following caveat, > > ========== > , unless you require that all boards (or device trees) define a system > hog pinmux configuration that muxes all required GPIO signals as desired. > ========== > > ... which might be appropriate for HW where GPIO-vs-special-function > selection is performed in the pinmux controller itself, per-pin. Perhaps > this is the OMAP special case you mentioned before? Yeah :-/ I worry about exploding complexity here, so we need to think about this a bit more... Linus -- 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/
