On 09/14/2013 01:08 AM, boris brezillon wrote: > Hello Stephen, > > Le 14/09/2013 00:40, Stephen Warren a écrit : >> On 09/13/2013 01:53 AM, Boris BREZILLON wrote: >>> AT91 SoCs do not support per pin debounce time configuration. >>> Instead you have to configure a debounce time which will be used for all >>> pins of a given bank (PIOA, PIOB, ...). ... >>> Required properties for pin configuration node: ... >>> -DEBOUNCE_VAL (0x3fff << 17): debounce val. >> >> This change would break the DT ABI since it removes a feature that's >> already present. ... >> I suppose it's still up to the Atmel maintainers to decide whether this >> is appropriate, or whether the impact to out-of-tree DT files would be >> problematic. >> >> Assuming the DT ABI can be broken, I think I'd prefer to do so, rather >> than take "non-alt" patch 4/4, since a per-pin DEBOUNCE_VAL clearly >> doesn't correctly model the HW, assuming the patch description is >> correct. I don't think arguments re: the generic pinconf debounce >> property hold; if the Linux-specific/internal generic property doesn't >> apply, the DT binding should not be bent to adjust to it, but should >> rather still represent the HW itself. > > What about the last point in my list: "reconfigure debounce after > startup" ? > > Here is an example that may be problematic: > > Let's say you have one device using multiple configuration of pins > ("default", "xxx", "yyy"). > The "default" config needs a particular debounce time on a given pin and > the "xxx" and "yyy" > configs need different debounce time on the same pin. > > How would you solve this with this patch approach ? Each state has a different pin configuration node, and hence can specify a different debounce value. This patch has no impact on that (it just changes whether the state-specific node specifies the debounce value in a single standalone property, or encodes it into each entry in the pins property, all within the same node). -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html