On Wed, 2023-08-30 at 17:29 +0100, Jonathan Cameron wrote: > On Fri, 4 Aug 2023 16:53:38 +0200 > Nuno Sa <nuno.sa@xxxxxxxxxx> wrote: > > > This is the initial RFC following the discussion in [1]. I'm aware this is > > by no means ready for inclusion and it's not even compilable since in > > the RFC I did not included the patch to add component_compare_fwnode() > > and component_release_fwnode(). > > Whilst I haven't read this through yet, I suspect Olivier will be able to > offer some insight on some of this and likewise you may be able to > point out pitfalls etc in his series (I see you did some review already :) > > https://lore.kernel.org/linux-iio/20230727150324.1157933-1-olivier.moysan@xxxxxxxxxxx/ > > Both are about multiple interacting components of an overall datapath. > Whether there is commonality isn't yet clear to me. > I made a very general comment in that series but I need to look better at it. Not sure if we can merge them together but let's see... > > > > The goal is to have a first feel on the > > direction of the framework so that if I need to drastically change it, > > better do it now. The RFC also brings the ad9647 and the axi_adc core to > > the same functionality we have now upstream with one extra fundamental > > feature that is calibrating the digital interface. This would be very > > difficult to do with the current design. Note that I don't expect any > > review on those drivers (rather than things related to the framework). > > > > I also want to bring up a couple of things that I've > > been thinking that I'm yet not sure about (so some feedback might make > > mind in one direction or another). > > > > 1) Im yet not sure if I should have different compatibles in the > > axi-adc-core driver. Note this soft core is a generic core and for every > > design (where the frontend device changes or has subtle changes like > > different number of data paths) there are subtle changes. So, the number > > of channels might be different, the available test patterns might be > > different, some ops might be available for some designs but not for > > others, etc... > > I don't suppose there is any chance Analog can make at least some of this > discoverable from the hardware? Capability registers etc in the long > run. Can't fix what is already out there. > Well, it is a soft core so my naive assumption is that it's doable if some HDL guy is willing to implement it. But yes, it might get supported only for new designs. > > With a different compatible we could fine tune > > those differences (with a chip_info like structure) and pass some const > > converter_config to the framework that would allow it to do more safety > > checks and potentially reduce the number of converter_ops. > > OTOH, starting to add all of these compatibles might become messy in the > > long run and will likely mean that we'll always have to change both > > drivers in order to support a new frontend. And the frontend devices > > should really be the ones having all the "knowledge" to configure the > > soft core even if it means more converter_ops (though devicetree might > > help as some features are really HW dependent). I more inclined to just > > leave things as-is in the RFC. > > I'm fine with putting this stuff in DT where possible. > > > > > 2) There are some IIO attributes (like scale, frequency, etc) that might > > be implemented in the soft cores. I still didn't made my mind if I should just > > have a catch all read_raw() and write_raw() converter_ops or more fine > > tuned ops. Having the catch all reduces the number of ops but also makes > > it more easier to add stuff that ends up being not used anymore and then > > forgotten. There are also cases (eg: setting sampling frequency) where > > we might need to apply settings in both the frontend and the backend > > devices which means having the catch all write_raw() would be more > > awkward in these case. I'm a bit more inclined to the more specific ops. > > It's the kernel - we can always change the internal API later as long as we > don't touch the user space part. Go with your gut feeling today and > if it changes this sort of refactor usually isn't that bad. > Agreed... > - Nuno Sá
