Re: [PATCH v4 5/7] ARM: dts: aspeed: yosemite5: Correct power monitor shunt resistor

[Kevin Tung]

On Mon, Feb 9, 2026 at 2:21 PM Andrew Jeffery
<andrew@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hi Kevin,
>
> On Fri, 2026-01-30 at 16:20 +0800, Kevin Tung wrote:
> > The shunt resistor value defined in the DTS was incorrect and did not
> > reflect the resistor value populated on the board. As a result, power
> > and current readings derived from this value were inaccurate.
>
> Okay, but how did it come to be incorrect in the devicetree? Was the
> documentation wrong and so someone entered the wrong value? Was the
> documentation correct but there was a misunderstanding? Did the
> hardware design change and the devicetree is now just inappropriate for
> your needs?
>
> Essentially, what's preventing this from happening again?
>

Hi Andrew,

The root cause is a hardware design change, which made the previous
devicetree configuration is inappropriate for our needs.
I have updated the commit message to reflect this.

The changes have been confirmed by our power team, verifying that the
power readings now match the latest hardware design.

> >
> > This change
> >
>
> I'd rather you rephrase this to avoid using "This change ...".
> Hopefully the commit message always refers to its change.
>
> Generally, please write in the imperative mood (see [1])
>
> [1]: https://docs.kernel.org/process/submitting-patches.html#describe-your-changes
>

Updated commit message to use imperative mood, thanks for the reference.

Kevin

> > updates the DTS to use the correct shunt resistor value
> > according to the hardware design, restoring accurate power and current
> > measurements.
> >
> > Signed-off-by: Kevin Tung <kevin.tung.openbmc@xxxxxxxxx>
> > ---
> >  arch/arm/boot/dts/aspeed/aspeed-bmc-facebook-yosemite5.dts | 14 +++++++-------
> >  1 file changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/arm/boot/dts/aspeed/aspeed-bmc-facebook-yosemite5.dts b/arch/arm/boot/dts/aspeed/aspeed-bmc-facebook-yosemite5.dts
> > index 84d3731b17f7c7c87338672bbcc859de2b89b722..524597a81365ef10cd03b67d35eeb88a965cbe0a 100644
> > --- a/arch/arm/boot/dts/aspeed/aspeed-bmc-facebook-yosemite5.dts
> > +++ b/arch/arm/boot/dts/aspeed/aspeed-bmc-facebook-yosemite5.dts
> > @@ -415,7 +415,7 @@ power-sensor@42 {
> >       power-monitor@43 {
> >               compatible = "lltc,ltc4287";
> >               reg = <0x43>;
> > -             shunt-resistor-micro-ohms = <250>;
> > +             shunt-resistor-micro-ohms = <100>;
> >       };
> >
> >       power-sensor@44 {
> > @@ -461,25 +461,25 @@ eeprom@57 {
> >       power-monitor@58 {
> >               compatible = "renesas,isl28022";
> >               reg = <0x58>;
> > -             shunt-resistor-micro-ohms = <1000>;
> > +             shunt-resistor-micro-ohms = <10000>;
> >       };
> >
> >       power-monitor@59 {
> >               compatible = "renesas,isl28022";
> >               reg = <0x59>;
> > -             shunt-resistor-micro-ohms = <1000>;
> > +             shunt-resistor-micro-ohms = <10000>;
> >       };
> >
> >       power-monitor@5a {
> >               compatible = "renesas,isl28022";
> >               reg = <0x5a>;
> > -             shunt-resistor-micro-ohms = <1000>;
> > +             shunt-resistor-micro-ohms = <10000>;
> >       };
> >
> >       power-monitor@5b {
> >               compatible = "renesas,isl28022";
> >               reg = <0x5b>;
> > -             shunt-resistor-micro-ohms = <1000>;
> > +             shunt-resistor-micro-ohms = <10000>;
> >       };
> >
> >       psu@5c {
> > @@ -723,13 +723,13 @@ gpio-expander@21 {
> >       power-sensor@40 {
> >               compatible = "ti,ina230";
> >               reg = <0x40>;
> > -             shunt-resistor = <2000>;
> > +             shunt-resistor = <1000>;
> >       };
> >
> >       power-sensor@41 {
> >               compatible = "ti,ina230";
> >               reg = <0x41>;
> > -             shunt-resistor = <2000>;
> > +             shunt-resistor = <1000>;
> >       };
> >
> >       power-sensor@42 {
>
> The way the commit message is written suggests it was just one shunt
> resistor, but that's clearly not the case.
>
> Andrew