linux-kernel - Re: [PATCH] arm64: dts: qcom: lemans-evk: Enable Bluetooth support

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Message-ID: <28ffece5-29b7-4d6f-a6cf-5fdf3b8259ef@oss.qualcomm.com>
Date: Mon, 10 Nov 2025 12:49:57 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Wei Deng <wei.deng@....qualcomm.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, linux-bluetooth@...r.kernel.org,
        stable@...r.kernel.org, cheng.jiang@....qualcomm.com,
        quic_jiaymao@...cinc.com, quic_chezhou@...cinc.com,
        quic_shuaz@...cinc.com
Subject: Re: [PATCH] arm64: dts: qcom: lemans-evk: Enable Bluetooth support

On 11/10/25 6:57 AM, Wei Deng wrote:
> There's a WCN6855 WiFi/Bluetooth module on an M.2 card. To make
> Bluetooth work, we need to define the necessary device tree nodes,
> including UART configuration and power supplies.
> 
> Since there is no standard M.2 binding in the device tree at present,
> the PMU is described using dedicated PMU nodes to represent the
> internal regulators required by the module.
> 
> The 3.3V supply for the module is assumed to come directly from the
> main board supply, which is 12V. To model this in the device tree, we
> add a fixed 12V regulator node as the DC-IN source and connect it to
> the 3.3V regulator node.
> 
> Signed-off-by: Wei Deng <wei.deng@....qualcomm.com>
> ---

[...]

>  &apps_rsc {
> @@ -627,6 +708,22 @@ &qupv3_id_2 {
>  	status = "okay";
>  };
>  
> +&qup_uart17_cts {
> +	bias-disable;
> +};
> +
> +&qup_uart17_rts {
> +	bias-pull-down;
> +};
> +
> +&qup_uart17_tx {
> +	bias-pull-up;
> +};
> +
> +&qup_uart17_rx {
> +	bias-pull-down;
> +};

This is notably different than all other platforms' bluetooth pin
settings - for example pulling down RX sounds odd, since UART signal
is supposed to be high at idle

see hamoa.dtsi : qup_uart14_default as an example

Konrad