On 06/12/16 11:12, Bartosz Golaszewski wrote: > 2016-12-03 10:11 GMT+01:00 Jonathan Cameron <jic23@xxxxxxxxxx>: >> On 30/11/16 10:10, Lars-Peter Clausen wrote: >>> On 11/29/2016 04:35 PM, Bartosz Golaszewski wrote: >>>> 2016-11-29 16:30 GMT+01:00 Lars-Peter Clausen <lars@xxxxxxxxxx>: >>>>> On 11/29/2016 04:22 PM, Bartosz Golaszewski wrote: >>>>> [...] >>>>>> diff --git a/Documentation/devicetree/bindings/iio/misc/iio-regulator.txt b/Documentation/devicetree/bindings/iio/misc/iio-regulator.txt >>>>>> new file mode 100644 >>>>>> index 0000000..147458f >>>>>> --- /dev/null >>>>>> +++ b/Documentation/devicetree/bindings/iio/misc/iio-regulator.txt >>>>>> @@ -0,0 +1,18 @@ >>>>>> +Industrial IO regulator device driver >>>>>> +------------------------------------- >>>>>> + >>>>>> +This document describes the bindings for the iio-regulator - a dummy device >>>>>> +driver representing a physical regulator within the iio framework. >>>>> >>>>> No bindings for drivers, only for hardware. So this wont work. >>>>> >>>> >>>> What about exporting regulator attributes analogous to the one in this >>>> patch from the iio-core when a *-supply property is specified for a >>>> node? >>> >>> The problem with exposing direct control to the regulator is that it allows >>> to modify the hardware state without the drivers knowledge. If you >>> power-cycle a device all previous configuration that has been written to the >>> device is reset. The device driver needs to be aware of this otherwise its >>> assumed state and the actual device state can divert which will result in >>> undefined behavior. Also access to the device will fail unexpectedly when >>> the regulator is turned off. So I think generally the driver should >>> explicitly control the regulator, power-up when needed, power-down when not. >> I agree with what Lars has said. >> >> There 'may' be some argument to ultimately have a bridge driver from >> regulators to IIO. That would be for cases where the divide between a regulator >> and a DAC is blurred. However it would still have to play nicely with the >> regulator framework and any other devices registered on that regulator. >> Ultimately the ideal in that case would then be to describe what the DAC is >> actually being used to do but that's a more complex issue! >> >> That doesn't seem to be what you are targeting here. >> >> What it sounds like you need is to have the hardware well enough described that >> the standard runtime power management can disable the regulator just fine when >> it is not in use. This may mean improving the power management in the relevant >> drivers. >> >> Jonathan >> >> p.s. If ever proposing to do something 'unusual' with a regulator you should >> bring in the regulator framework maintainers in the cc list. >>> >>> - Lars >>> >> > > I wrote the initial patch quickly and didn't give it much of a > thought. Now I realized I completely missed the point and managed to > confuse everybody - myself included. > > So the problem we have is not power-cycling the adc - it's > power-cycling the device connected to a probe on which there's an adc. > What I was trying to do was adding support for the power-switch on > baylibre-acme[1] probes. > > For example: we have a USB probe on which the VBUS signal goes through > a power load switch and than through the adc. The adc (in this case > ina226) is always powered on, while the fixed regulator I wanted to > enable/disable actually drives the power switch to cut/restore power > to the connected USB device i.e. there's no real regulator - just a > GPIO driving the power switch. > > A typical use case is measuring the power consumption of development > boards[2]. Rebooting them remotely using acme probes is already done, > but we're using the obsolete /sys/class/gpio interface. > > We're already using libiio to read the measured data from the power > monitor, that's why we'd like to use the iio framework for > power-cycling the devices as well. My question is: would bridging the > regulator framework be the right solution? Should we look for > something else? Bridge the GPIO framework instead? Definitely doesn't fit inside standard scope of IIO - though I can see why you were thinking along these lines. Mark Brown, any thoughts? Effectively we are are looking at something that (in general form) might be the equivalent of controlling a lab bench supply... So regulators at the edge of the known world, with no visibility of what lies beyond. > > Best regards, > Bartosz Golaszewski > > [1] http://baylibre.com/acme/ > [2] https://github.com/BayLibre/POWERCI > -- > 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 > -- 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
