On 2017-11-11 01:33, Jonathan Cameron wrote: > On Mon, 6 Nov 2017 08:19:58 +0100 > Martin Kepplinger <martink@xxxxxxxxx> wrote: > >> This adds the power_mode sysfs interface to the device as documented in >> sysfs-bus-iio. >> >> --- >> >> Note that I explicitely don't sign off on this. >> >> This is a starting point for anybody who can test it and check for correct >> API usage, and ABI correctness, as documented in Documentation/ABI/testing/sys-bus-iio >> (grep it for "power_mode"). The ABI doc probably would need an addition >> too, if the 4 power modes here seem generally useful (there are only >> 2 listed there)! >> >> So, if you can test this, feel free to set up a proper patch or >> two, and I'm happy to review. >> >> Please note that this patch is quite old. It really should be that simple >> as far as my understanding back then. We always list the available frequencies >> of the given power mode we are in, for example, already, and everything >> basically is in place except for the user interface. > > Hmm. A lot of devices support something along these lines. The issue > has always been - how is userspace to figure out what to do with it? > It's all very vague... > > Funnily enough - this used to be really common, but is becoming less so > now - presumably because no one was using it much (or maybe I am reading > too much into that ;) > > Now the question is whether it can be tied to better defined things? > > Here low noise restricts the range to 4g. Issue is that we don't actually > have writeable _available attributes (which correspond to range in this case). > Does it? Isn't it merely less oversampling. > Low power mode... This one is apparently oversampling. If possible support > it as that as we have well defined interfaces for that. > > Jonathan. Ah, I remember; the oversampling settings was actually a reason why I hadn't submitted the patch :) The oversampling API would definitely be more accurate. I would like "oversampling" more than this "power_mode" too. For this driver it would be far more complicated to implement though. I doubt that it'll be done. power_mode is basically already there implicitely, and given that there *is* the ABI, we could offer it for free. But given your concerns, I would strip down this patch to only offer the already documented "low_noise" and "low_power" modes. It wouldn't be worth it to extend the ABI just because of this! Users would have a simple switch if they don't really *want* to know the details. I think it can be useful to just say "I don't care about power consuption. Be as accurate as possible" or "I just want this think to work. Use a little power as possible." Sure it's vage, but would it be useless? -- 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
