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? Best regards, Bartosz Golaszewski [1] http://baylibre.com/acme/ [2] https://github.com/BayLibre/POWERCI -- 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
