On 05/22/2018 07:08 PM, Jonathan Cameron wrote: >>>> +* Quadrature x2 Rising: >>>> + Rising edges on either quadrature pair signals updates the respective >>>> + count. Quadrature encoding determines the direction. >>> This one I've never met. Really? There are devices who do this form >>> of crazy? It gives really uneven counting and I'm failing to see when >>> it would ever make sense... References for these odd corner cases >>> would be good. >>> >>> >>> __|---|____|-----|____ >>> ____|----|____|-----|____ >>> >>> 001122222223334444444 >> That's the same reaction I had when I discovered this -- in fact the >> STM32 LP Timer is the first time I've come across such a quadrature >> mode. I'm not sure of the use case for this mode, because positioning >> wouldn't be precise as you've pointed out. Perhaps Fabrice or Benjamin >> can probe the ST guys responsible for this design choice to figure out >> the rationale. > Hmm. My inclination would be to not support it unless someone can up > with a meaningful use. We are adding ABI (be it not much) for a case > that to us makes no sense. Hi Jonathan, William, Sorry for the late reply. To follow your advise, we can probably drop this for now. I think simple counter, or quadrature x4 will be mostly used for now. As you pointed out, there's not much ABI for x2 rising/falling cases. It will not be a big deal to add it later if needed. I can help to update (remove & test) this in LP-Timer counter driver if you wish. Please let me know, Thanks, Fabrice > > Looks rather like the sort of thing that is a side effect of the > implementation rather than deliberate. > >> I'm leaving in these modes for now, as they do exist in the STM32 LP >> Timer, but it does make me curious what the intentions for them were >> (perhaps use cases outside of traditional quadrature encoder >> positioning). >> > Sure if there is a usecase then fair enough. > > Jonathan > > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
