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

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Message-ID: <ee04e03a-ffd0-43c0-ba77-c7ee20aaac43@oss.qualcomm.com>
Date: Tue, 11 Nov 2025 20:24:19 +0800
From: Wei Deng <wei.deng@....qualcomm.com>
To: Konrad Dybcio <konrad.dybcio@....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

Hi Konrad,

Thanks for your comments.

On 11/10/2025 7:49 PM, Konrad Dybcio wrote:
> 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
> 

I followed the qup_uart17 settings from lemans-ride-common.dtsi. Since these configurations are not required for Bluetooth functionality. I will remove this configuration in the next patch.

> Konrad

-- 
Best Regards,
Wei Deng