On 3/3/19 5:07 PM, Harald Geyer wrote: > Marek Vasut writes: >> On 2/19/19 11:10 AM, Harald Geyer wrote: >>> Marek Vasut writes: >>>> On 2/18/19 11:18 PM, Harald Geyer wrote: >>>>> From the explanations provided by Mark it is clear that this property >>>>> is an artifact of the implementation in linux. I think we should document >>>>> is as such. How about: >>>>> >>>>> gpios-states : On operating systems, that don't support reading back gpio >>>>> values in output mode (most notably linux), this array >>>>> provides the state of GPIO pins set when requesting them >>>>> from the gpio controller. >>>> >>>> That's good. >>>> >>>>> Systems, that are capable of >>>>> preserving state when requesting the lines, are free to >>>>> ignore this property. >>>> >>>> Are they ? >>> >>> I think so. Also this seems to be what Mark wrote yesterday: >>> >>> | With the GPIO API as it stands it is unfortunately not possible to >>> | preserve the state, if the API were fixed we'd preserve state. >>> >>>> I think there are systems which depend on preconfiguring the >>>> GPIO according to this property. >>> >>> These systems need to preconfigure the GPIOs in firmware anyway, so >>> they should be fine so long as the driver preserves state. >>> >>> Since the original wording doesn't give any guarantees, I think the >>> new wording doesn't change anything. It just makes it clearer, that >>> there are no guarantees and that some drivers will happily overwrite >>> state when this property is absent. >> >> OK, so how can we move forward with this ? We discussed a lot, but I >> don't know what we should do about the patch. > > Yes, we discussed a lot. I guess most people lost track of where we > stand. I'd suggest you send a V2 of the patch, picking up all the proposed > changes. If you feel the part about `gpios-states' property is too > controversial, then maybe split it in two patches: The first containing > the non-controversial changes and the second improving `gpios-states' > description, so that maintainers can ACK them independently. Well what are the proposed changes ? I don't think there was any agreement on them. -- Best regards, Marek Vasut
