On 05/11/2012 01:51 PM, Tony Lindgren wrote: > * Stephen Warren <swarren@xxxxxxxxxxxxx> [120511 12:21]: >> >> The mapping of GPIO to pinctrl pins would presumably be driven solely by >> the HW design of the pin controller and GPIO, and not by the mux >> selection in the pin controller (otherwise, I'd argue this isn't a >> simple case that should be handled by pinctrl-simple). >> >> As such, I'd expect some properties/table at the top-level of the pin >> controller object to describe the GPIO mapping. In turn, that implies >> that the individual per-pin mux-selection/configuration nodes don't need >> to describe any GPIO-related information. > > Yes good point. I agree it's a HW design issue, and could be in the properties > for the pin controller object. > > Just to summarize, the things to consider with the GPIO to mux mapping are: > > 1. Having this table as static data in the driver is is not a nice > solution as it seems that we'd currently need six mapping tables for > omap2+ alone. > > 2. This table is not needed for most of the (hundreds of) pins, it's > only needed for a few selected pins, let's say ten or so on an average > device. So there's no need to stuff the kernel with information about > the unused GPIO pins. > > It seems that the conclusion here is that we don't need to worry about > GPIOs in the pinctrl-simple binding for now, and it can be added later > without having to change the basic binding. The one thing I wanted to resolve here wasn't so much the binding for GPIO interaction here, but the following comment: You wrote: > I wrote: >> From a binding perspective, I don't see why you'd want to allow two cases: >> >> 1) One node with multiple entries in pinctrl-simple,cells >> 2) Multiple nodes each with a single entry in pinctrl-simple,cells >> >> Why not only allow (1)? > > Because we need to specify GPIO for some pins. There may be additional flags > too, we do have external DMA request lines for few pins available.. I'm not > saying pinctrl fwk should know about that, but it's a similar mapping of pins > to GPIO lines. I'm asserting that since any GPIO mapping information would be at the top-level of the pinctrl-simple binding, we can in fact only allow option (1) above for the individual pin configuration nodes. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
