On 06/12/16 11:12, Bartosz Golaszewski wrote:

2016-12-03 10:11 GMT+01:00 Jonathan Cameron [off-list ref]:

quoted

On 30/11/16 10:10, Lars-Peter Clausen wrote:

quoted

On 11/29/2016 04:35 PM, Bartosz Golaszewski wrote:

quoted

2016-11-29 16:30 GMT+01:00 Lars-Peter Clausen [off-list ref]:

quoted

On 11/29/2016 04:22 PM, Bartosz Golaszewski wrote:
[...]

quoted

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.

quoted

- 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
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