Configuring shunt_resistor in hwmon

Configuring shunt_resistor in hwmon

[Alex Qiu]

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Hi OpenBMC folks,

Is there a way to configure the shunt_resistor value for a hwmon with
entity-manager or other modules? We need to configure this value to make
the INA230 report correct voltage, but for now I don't find anything in the
code for it. Shall this be a feature to implement? Thanks!

- Alex Qiu

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Re: Configuring shunt_resistor in hwmon

[James Feist]

On 1/6/20 1:16 PM, Alex Qiu wrote:
> Hi OpenBMC folks,
> 
> Is there a way to configure the shunt_resistor value for a hwmon with 
> entity-manager or other modules?

Have you seen this? 
https://github.com/openbmc/entity-manager/blob/0cbe6bf34101bab7544b40011868efc5145c0804/configurations/WFT%20Baseboard.json#L7

For Entity-Manager + dbus-sensors.

> We need to configure this value to make 
> the INA230 report correct voltage, but for now I don't find anything in 
> the code for it. Shall this be a feature to implement? Thanks!
> 
> - Alex Qiu

Re: Configuring shunt_resistor in hwmon

[Alex Qiu]

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Hi James,

Thanks for your quick reply and reviewing my code in the morning!

That looks interesting, so this ScaleFactor will be used to multiply the
voltage value from hwmon without setting the shunt_resistor explicitly? I
do have a little concern on the resolution, because it's only reporting
0.165V with default shunt_resistor setting, but we'll try and see if this
will work for our case. In the meantime, do you know any other method that
will work?

Thank you!

- Alex Qiu


On Mon, Jan 6, 2020 at 1:21 PM James Feist <james.feist@linux.intel.com>
wrote:

> On 1/6/20 1:16 PM, Alex Qiu wrote:
> > Hi OpenBMC folks,
> >
> > Is there a way to configure the shunt_resistor value for a hwmon with
> > entity-manager or other modules?
>
> Have you seen this?
>
> https://github.com/openbmc/entity-manager/blob/0cbe6bf34101bab7544b40011868efc5145c0804/configurations/WFT%20Baseboard.json#L7
>
> For Entity-Manager + dbus-sensors.
>
> > We need to configure this value to make
> > the INA230 report correct voltage, but for now I don't find anything in
> > the code for it. Shall this be a feature to implement? Thanks!
> >
> > - Alex Qiu
>

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Re: Configuring shunt_resistor in hwmon

[James Feist]

On 1/6/20 1:29 PM, Alex Qiu wrote:
> Hi James,
> 
> Thanks for your quick reply and reviewing my code in the morning!
> 
> That looks interesting, so this ScaleFactor will be used to multiply the 
> voltage value from hwmon without setting the shunt_resistor explicitly? 
> I do have a little concern on the resolution, because it's only 
> reporting 0.165V with default shunt_resistor setting, but we'll try and 
> see if this will work for our case. In the meantime, do you know any 
> other method that will work?

That's all I'm aware of in dbus-sensors. We have a voltage divider 
in-front of our ADC channels, so we use this scale factor to calculate 
the actual voltage. Anything else I think you'd need to add as a new 
change if you're using dbus-sensors. I'm not sure if phosphor-hwmon 
offers anything you could use or not.

> 
> Thank you!
> 
> - Alex Qiu
> 
> 
> On Mon, Jan 6, 2020 at 1:21 PM James Feist <james.feist@linux.intel.com 
> <mailto:james.feist@linux.intel.com>> wrote:
> 
>     On 1/6/20 1:16 PM, Alex Qiu wrote:
>      > Hi OpenBMC folks,
>      >
>      > Is there a way to configure the shunt_resistor value for a hwmon
>     with
>      > entity-manager or other modules?
> 
>     Have you seen this?
>     https://github.com/openbmc/entity-manager/blob/0cbe6bf34101bab7544b40011868efc5145c0804/configurations/WFT%20Baseboard.json#L7
> 
>     For Entity-Manager + dbus-sensors.
> 
>      > We need to configure this value to make
>      > the INA230 report correct voltage, but for now I don't find
>     anything in
>      > the code for it. Shall this be a feature to implement? Thanks!
>      >
>      > - Alex Qiu
> 

Re: Configuring shunt_resistor in hwmon

[Alex Qiu]

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Hi James,

Got it. Thank you for the answer!

- Alex Qiu


On Mon, Jan 6, 2020 at 1:37 PM James Feist <james.feist@linux.intel.com>
wrote:

> On 1/6/20 1:29 PM, Alex Qiu wrote:
> > Hi James,
> >
> > Thanks for your quick reply and reviewing my code in the morning!
> >
> > That looks interesting, so this ScaleFactor will be used to multiply the
> > voltage value from hwmon without setting the shunt_resistor explicitly?
> > I do have a little concern on the resolution, because it's only
> > reporting 0.165V with default shunt_resistor setting, but we'll try and
> > see if this will work for our case. In the meantime, do you know any
> > other method that will work?
>
> That's all I'm aware of in dbus-sensors. We have a voltage divider
> in-front of our ADC channels, so we use this scale factor to calculate
> the actual voltage. Anything else I think you'd need to add as a new
> change if you're using dbus-sensors. I'm not sure if phosphor-hwmon
> offers anything you could use or not.
>
> >
> > Thank you!
> >
> > - Alex Qiu
> >
> >
> > On Mon, Jan 6, 2020 at 1:21 PM James Feist <james.feist@linux.intel.com
> > <mailto:james.feist@linux.intel.com>> wrote:
> >
> >     On 1/6/20 1:16 PM, Alex Qiu wrote:
> >      > Hi OpenBMC folks,
> >      >
> >      > Is there a way to configure the shunt_resistor value for a hwmon
> >     with
> >      > entity-manager or other modules?
> >
> >     Have you seen this?
> >
> https://github.com/openbmc/entity-manager/blob/0cbe6bf34101bab7544b40011868efc5145c0804/configurations/WFT%20Baseboard.json#L7
> >
> >     For Entity-Manager + dbus-sensors.
> >
> >      > We need to configure this value to make
> >      > the INA230 report correct voltage, but for now I don't find
> >     anything in
> >      > the code for it. Shall this be a feature to implement? Thanks!
> >      >
> >      > - Alex Qiu
> >
>

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Re: Configuring shunt_resistor in hwmon

[Vijay Khemka]

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You should be able to define this value in device tree. Or you can calculate scale factor and use it in entity manager.

From: openbmc <openbmc-bounces+vijaykhemka=fb.com@lists.ozlabs.org> on behalf of Alex Qiu <xqiu@google.com>
Date: Monday, January 6, 2020 at 1:18 PM
To: "openbmc@lists.ozlabs.org" <openbmc@lists.ozlabs.org>
Cc: Josh Lehan <krellan@google.com>, Kais Belgaied <belgaied@google.com>, Devjit Gopalpur <devjitg@google.com>, Peter Lundgren <peterlundgren@google.com>
Subject: Configuring shunt_resistor in hwmon

Hi OpenBMC folks,

Is there a way to configure the shunt_resistor value for a hwmon with entity-manager or other modules? We need to configure this value to make the INA230 report correct voltage, but for now I don't find anything in the code for it. Shall this be a feature to implement? Thanks!

- Alex Qiu

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Re: Configuring shunt_resistor in hwmon

[Alex Qiu]

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Hi Vijay, I don't know about the device tree yet, and I will look for info
about it. Thanks!

- Alex Qiu


On Mon, Jan 6, 2020 at 3:37 PM Vijay Khemka <vijaykhemka@fb.com> wrote:

> You should be able to define this value in device tree. Or you can
> calculate scale factor and use it in entity manager.
>
>
>
> *From: *openbmc <openbmc-bounces+vijaykhemka=fb.com@lists.ozlabs.org> on
> behalf of Alex Qiu <xqiu@google.com>
> *Date: *Monday, January 6, 2020 at 1:18 PM
> *To: *"openbmc@lists.ozlabs.org" <openbmc@lists.ozlabs.org>
> *Cc: *Josh Lehan <krellan@google.com>, Kais Belgaied <belgaied@google.com>,
> Devjit Gopalpur <devjitg@google.com>, Peter Lundgren <
> peterlundgren@google.com>
> *Subject: *Configuring shunt_resistor in hwmon
>
>
>
> Hi OpenBMC folks,
>
>
>
> Is there a way to configure the shunt_resistor value for a hwmon with
> entity-manager or other modules? We need to configure this value to make
> the INA230 report correct voltage, but for now I don't find anything in the
> code for it. Shall this be a feature to implement? Thanks!
>
>
> - Alex Qiu
>

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Re: Configuring shunt_resistor in hwmon

[Lei YU]

On Tue, Jan 7, 2020 at 5:38 AM James Feist <james.feist@linux.intel.com> wrote:
>
> On 1/6/20 1:29 PM, Alex Qiu wrote:
> > Hi James,
> >
> > Thanks for your quick reply and reviewing my code in the morning!
> >
> > That looks interesting, so this ScaleFactor will be used to multiply the
> > voltage value from hwmon without setting the shunt_resistor explicitly?
> > I do have a little concern on the resolution, because it's only
> > reporting 0.165V with default shunt_resistor setting, but we'll try and
> > see if this will work for our case. In the meantime, do you know any
> > other method that will work?
>
> That's all I'm aware of in dbus-sensors. We have a voltage divider
> in-front of our ADC channels, so we use this scale factor to calculate
> the actual voltage. Anything else I think you'd need to add as a new
> change if you're using dbus-sensors. I'm not sure if phosphor-hwmon
> offers anything you could use or not.

With phosphor-hwmon, you could define GAIN, OFFSET in the config file
to adjust the reading.
See details in
https://github.com/openbmc/docs/blob/master/architecture/sensor-architecture.md#my-sensors-are-not-defined-in-an-mrw

Re: Configuring shunt_resistor in hwmon

[Alex Qiu]

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Hi Lei,

I'm not sure if we're using phosphor-hwmon, but I'll take a look. Thank you!

- Alex Qiu


On Mon, Jan 6, 2020 at 7:20 PM Lei YU <mine260309@gmail.com> wrote:

> On Tue, Jan 7, 2020 at 5:38 AM James Feist <james.feist@linux.intel.com>
> wrote:
> >
> > On 1/6/20 1:29 PM, Alex Qiu wrote:
> > > Hi James,
> > >
> > > Thanks for your quick reply and reviewing my code in the morning!
> > >
> > > That looks interesting, so this ScaleFactor will be used to multiply
> the
> > > voltage value from hwmon without setting the shunt_resistor explicitly?
> > > I do have a little concern on the resolution, because it's only
> > > reporting 0.165V with default shunt_resistor setting, but we'll try and
> > > see if this will work for our case. In the meantime, do you know any
> > > other method that will work?
> >
> > That's all I'm aware of in dbus-sensors. We have a voltage divider
> > in-front of our ADC channels, so we use this scale factor to calculate
> > the actual voltage. Anything else I think you'd need to add as a new
> > change if you're using dbus-sensors. I'm not sure if phosphor-hwmon
> > offers anything you could use or not.
>
> With phosphor-hwmon, you could define GAIN, OFFSET in the config file
> to adjust the reading.
> See details in
>
> https://github.com/openbmc/docs/blob/master/architecture/sensor-architecture.md#my-sensors-are-not-defined-in-an-mrw
>

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