linux-kernel - Re: [PATCH 2/2] arm64: dts: qcom: sdm845-starqltechn: add slpi support

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Message-ID: <f00cb00d-1e0b-4968-9f5a-df3ce0d8c8db@oss.qualcomm.com>
Date: Fri, 12 Sep 2025 14:24:19 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Dzmitry Sankouski <dsankouski@...il.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] arm64: dts: qcom: sdm845-starqltechn: add slpi
 support

On 9/11/25 10:56 PM, Dzmitry Sankouski wrote:
> Add support for Qualcomm sensor low power island.
> 
> Signed-off-by: Dzmitry Sankouski <dsankouski@...il.com>
> ---
>  .../boot/dts/qcom/sdm845-samsung-starqltechn.dts   | 24 ++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sdm845-samsung-starqltechn.dts b/arch/arm64/boot/dts/qcom/sdm845-samsung-starqltechn.dts
> index 32ce666fc57e..2c1157ee7b2d 100644
> --- a/arch/arm64/boot/dts/qcom/sdm845-samsung-starqltechn.dts
> +++ b/arch/arm64/boot/dts/qcom/sdm845-samsung-starqltechn.dts
> @@ -902,6 +902,14 @@ &ipa {
>  	status = "okay";
>  };
>  
> +&slpi_pas {
> +	firmware-name = "qcom/sdm845/starqltechn/slpi.mbn";
> +	pinctrl-0 = <&slpi_ldo_active_state>;
> +	pinctrl-1 = <&slpi_ldo_sleep_state>;

It would perhaps make sense to model it as a GPIO regulator..

I found a downstream kernel for this device and it seems like
this is indeed a Samsung addition

The vendor kernel gates the regulator when the SLPI is shut
off, but I think it would be reasonable to keep it always-on
given you don't really want that to happen, and if you need
to restart the subsystem, not pulsing the regulator should
also likely work
> +	pinctrl-names = "default", "sleep";
> +	status = "okay";

a newline before status is customary

> +};
> +
>  &usb_1 {
>  	status = "okay";
>  };
> @@ -1028,6 +1036,22 @@ sd_card_det_n_state: sd-card-det-n-state {
>  		bias-pull-up;
>  	};
>  
> +	slpi_ldo_active_state: slpi-ldo-active-state {
> +		pins = "gpio8";
> +		function = "gpio";
> +		drive-strength = <2>;
> +		bias-disable;
> +		output-high;

Modeling the gpio-regulator will let you get rid of output-
properties here, which are discouraged in favor of gpiod_ APIs
in drivers

Konrad

> +	};
> +
> +	slpi_ldo_sleep_state: slpi-ldo-sleep-state {
> +		pins = "gpio8";
> +		function = "gpio";
> +		drive-strength = <2>;
> +		bias-disable;
> +		output-low;
> +	};
> +
>  	touch_irq_state: touch-irq-state {
>  		pins = "gpio120";
>  		function = "gpio";
>