Re: [PATCH v2 2/3] arm64: dts: qcom: pm8916: Add BMS and charger

[Konrad Dybcio]

On 10/26/23 21:17, Stephan Gerhold wrote:
> On Thu, Oct 26, 2023 at 08:54:00PM +0200, Konrad Dybcio wrote:
> > On 10/24/23 11:29, Nikita Travkin wrote:
> > > Konrad Dybcio писал(а) 24.10.2023 13:34:
> > > > On 10/23/23 08:20, Nikita Travkin wrote:
> > > > > pm8916 contains some hardware blocks for battery powered devices:
> > > > >
> > > > > - VM-BMS: Battery voltage monitoring block.
> > > > > - LBC: Linear battery charger.
> > > > >
> > > > > Add them to the pmic dtsi so the devices that make use of those blocks
> > > > > can enable them.
> > > > >
> > > > > Signed-off-by: Nikita Travkin <nikita@xxxxxxx>
> > > > > ---
> > > > >     arch/arm64/boot/dts/qcom/pm8916.dtsi | 48 ++++++++++++++++++++++++++++++++++++
> > > > >     1 file changed, 48 insertions(+)
> > > > >
> > > > > diff --git a/arch/arm64/boot/dts/qcom/pm8916.dtsi b/arch/arm64/boot/dts/qcom/pm8916.dtsi
> > > > > index f4de86787743..4b2e8fb47d2d 100644
> > > > > --- a/arch/arm64/boot/dts/qcom/pm8916.dtsi
> > > > > +++ b/arch/arm64/boot/dts/qcom/pm8916.dtsi
> > > > > @@ -41,6 +41,35 @@ watchdog {
> > > > >     			};
> > > > >     		};
> > > > >     +		pm8916_charger: charger@1000 {
> > > > > +			compatible = "qcom,pm8916-lbc";
> > > > > +			reg = <0x1000>, <0x1200>, <0x1300>, <0x1600>;
> > > > > +			reg-names = "chgr", "bat_if", "usb", "misc";
> > > > > +
> > > > > +			interrupts = <0x0 0x10 0 IRQ_TYPE_EDGE_BOTH>,
> > > > > +				     <0x0 0x10 5 IRQ_TYPE_EDGE_BOTH>,
> > > > > +				     <0x0 0x10 6 IRQ_TYPE_EDGE_BOTH>,
> > > > > +				     <0x0 0x10 7 IRQ_TYPE_EDGE_BOTH>,
> > > > > +				     <0x0 0x12 0 IRQ_TYPE_EDGE_BOTH>,
> > > > > +				     <0x0 0x12 1 IRQ_TYPE_EDGE_BOTH>,
> > > > > +				     <0x0 0x13 0 IRQ_TYPE_EDGE_BOTH>,
> > > > > +				     <0x0 0x13 1 IRQ_TYPE_EDGE_BOTH>,
> > > > > +				     <0x0 0x13 2 IRQ_TYPE_EDGE_BOTH>,
> > > > > +				     <0x0 0x13 4 IRQ_TYPE_EDGE_BOTH>;
> > > > > +			interrupt-names = "vbat_det",
> > > > > +					  "fast_chg",
> > > > > +					  "chg_fail",
> > > > > +					  "chg_done",
> > > > > +					  "bat_pres",
> > > > > +					  "temp_ok",
> > > > > +					  "coarse_det",
> > > > > +					  "usb_vbus",
> > > > So, both the charger and the USBIN driver use the same irq? :/
> > >
> > > AFAIU the usbin extcon driver pretty much just tracks the state
> > > of the IRQ to report extcon. It happens to assume the same part
> > > of the pmic though, yes, which also means there will be no user
> > > that would enable both charger and vbus extcon, since charger
> > > driver provides this functionality as well.
> > So, should USBIN be removed from PM8916 dt since it's essentially
> > a part of the charger block?
>
> The "USB_IN" pad of the PM8916 seems to be connected on pretty much all
> devices, even if they are using external chargers and the charging
> functionality of PM8916 is completely disabled. For those devices, the
> &pm8916_usbin device provides a convenient way to detect the USB state,
> even without a working charger driver.
>
> While we could modify the PM8916 charger driver and DT node to have some
> special mode where charging and battery monitoring is completely
> disabled and only the USBIN extcon is provided, I'm not sure if that
> would provide a significant advantage compared to just keeping the
> simple &pm8916_usbin node with the existing driver.
Hmm okay I see..

Generally it's rather "no bueno" to have two DT nodes consuming the
same register space.. What happens when you enable BMS on a device
with a non-PM8916 charger? Does it correctly recognize "no battery"
etc.?

Konrad