[1/2] dt-bindings: iio: imo: mpu6050: add vdd-supply

inv_mpu6050 now supports an additional vdd-supply; document it.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
---
 Documentation/devicetree/bindings/iio/imu/inv_mpu6050.txt | 1 +
 1 file changed, 1 insertion(+)

Hi JB,

On Wed, Nov 06, 2019 at 07:55:20PM +0000, Jean-Baptiste Maneyrol wrote:
> Hello Stephan,
> 
> nice patch but I have an important concern.
> 
> We are calling the core_enable/disable_regulator functions when going into suspend and resume.
> With your changes, we are going to power down the chip when going into suspend and then power it up again.
> This way we will loose all already set configuration, like FSR, sampling rate, init values, ...
> The chip will not be able to work correctly anymore after a suspend-resume cycle.
> 
> You need to change the resume/suspend handlers to only disable/enable the vddio regulator, not the vdd one.

That is a good point, thanks!
I guess we are not able to use the regulator bulk API in this case...

I will send a v2 soon.

Stephan

Hi Stephan,

I think the regulator_bulk usage is good, and the core_enable/disable_regulator functions implemented the way you did is perfect for the init/shutdown phase.

We just need to change the suspend/resume implementation to use something different.

Thanks,
JB


From: linux-iio-owner@vger.kernel.org <linux-iio-owner@vger.kernel.org> on behalf of Stephan Gerhold <stephan@gerhold.net>

Sent: Wednesday, November 6, 2019 22:36

To: Jean-Baptiste Maneyrol <JManeyrol@invensense.com>

Cc: Jonathan Cameron <jic23@kernel.org>; Hartmut Knaack <knaack.h@gmx.de>; Lars-Peter Clausen <lars@metafoo.de>; Peter Meerwald-Stadler <pmeerw@pmeerw.net>; Rob Herring <robh+dt@kernel.org>; Mark Rutland <mark.rutland@arm.com>; Linus Walleij <linus.walleij@linaro.org>;
 Brian Masney <masneyb@onstation.org>; Jonathan Marek <jonathan@marek.ca>; linux-iio@vger.kernel.org <linux-iio@vger.kernel.org>; devicetree@vger.kernel.org <devicetree@vger.kernel.org>; linux-kernel@vger.kernel.org <linux-kernel@vger.kernel.org>

Subject: Re: [PATCH 2/2] iio: imu: mpu6050: Add support for vdd-supply regulator

 


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Hi JB,



On Wed, Nov 06, 2019 at 07:55:20PM +0000, Jean-Baptiste Maneyrol wrote:

> Hello Stephan,

> 

> nice patch but I have an important concern.

> 

> We are calling the core_enable/disable_regulator functions when going into suspend and resume.

> With your changes, we are going to power down the chip when going into suspend and then power it up again.

> This way we will loose all already set configuration, like FSR, sampling rate, init values, ...

> The chip will not be able to work correctly anymore after a suspend-resume cycle.

> 

> You need to change the resume/suspend handlers to only disable/enable the vddio regulator, not the vdd one.



That is a good point, thanks!

I guess we are not able to use the regulator bulk API in this case...



I will send a v2 soon.



Stephan

On Wed, Nov 6, 2019 at 7:37 PM Stephan Gerhold <stephan@gerhold.net> wrote:

> inv_mpu6050 now supports an additional vdd-supply; document it.
>
> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

On Thu, Nov 07, 2019 at 01:29:33PM +0000, Jean-Baptiste Maneyrol wrote:
> Hi Stephan,
> 
> I think the regulator_bulk usage is good, and the core_enable/disable_regulator functions implemented the way you did is perfect for the init/shutdown phase.
> 
> We just need to change the suspend/resume implementation to use something different.

As far as I can tell, the regulator bulk API is designed to be used when
you want to enable/disable multiple regulators at the same time.
It does not really allow controlling one of its regulators separately
(in a clean way).

E.g. if you would use regulator_bulk_disable() but already disabled one
of the regulators at some point earlier, you would run into a warning
because the regulator is disabled twice.

My updated patch is still clean enough (in my opinion), so I would say
it is better to avoid the regulator bulk API for this situation.
I will send v2 shortly.

Thanks,
Stephan