Re: [PATCH v2 4/4] arm64: dts: qcom: sm7225-fairphone-fp4: Add Bluetooth

Re: [PATCH v2 4/4] arm64: dts: qcom: sm7225-fairphone-fp4: Add Bluetooth

[Conor Dooley]

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On Fri, May 12, 2023 at 03:58:26PM +0200, Luca Weiss wrote:

> +&qup_uart1_cts {
> +	/*
> +	 * Configure a bias-bus-hold on CTS to lower power
> +	 * usage when Bluetooth is turned off. Bus hold will
> +	 * maintain a low power state regardless of whether
> +	 * the Bluetooth module drives the pin in either
> +	 * direction or leaves the pin fully unpowered.
> +	 */
> +	bias-bus-hold;
> +};
> +
> +&qup_uart1_rts {
> +	/* We'll drive RTS, so no pull */
> +	drive-strength = <2>;
> +	bias-disable;
> +};
> +
> +&qup_uart1_rx {
> +	/*
> +	 * Configure a pull-up on RX. This is needed to avoid
> +	 * garbage data when the TX pin of the Bluetooth module is
> +	 * in tri-state (module powered off or not driving the
> +	 * signal yet).
> +	 */
> +	bias-pull-up;
> +};
> +
> +&qup_uart1_tx {
> +	/* We'll drive TX, so no pull */
> +	drive-strength = <2>;
> +	bias-disable;
> +};

I recently made some changes to pincfg-node.yaml to detect if there's
conflicting properties used, and these got detected. Should these not
do what has been done on the msm8998-xiaomi-sagit, and delete the
inherited bias-foo from the dtsi?
&blsp1_i2c5_sleep {
	/delete-property/ bias-pull-up;
	bias-disable;
};

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Re: [PATCH v2 4/4] arm64: dts: qcom: sm7225-fairphone-fp4: Add Bluetooth

[Luca Weiss]

On Tue Mar 10, 2026 at 7:02 PM CET, Conor Dooley wrote:
> On Fri, May 12, 2023 at 03:58:26PM +0200, Luca Weiss wrote:
>
>> +&qup_uart1_cts {
>> +	/*
>> +	 * Configure a bias-bus-hold on CTS to lower power
>> +	 * usage when Bluetooth is turned off. Bus hold will
>> +	 * maintain a low power state regardless of whether
>> +	 * the Bluetooth module drives the pin in either
>> +	 * direction or leaves the pin fully unpowered.
>> +	 */
>> +	bias-bus-hold;
>> +};
>> +
>> +&qup_uart1_rts {
>> +	/* We'll drive RTS, so no pull */
>> +	drive-strength = <2>;
>> +	bias-disable;
>> +};
>> +
>> +&qup_uart1_rx {
>> +	/*
>> +	 * Configure a pull-up on RX. This is needed to avoid
>> +	 * garbage data when the TX pin of the Bluetooth module is
>> +	 * in tri-state (module powered off or not driving the
>> +	 * signal yet).
>> +	 */
>> +	bias-pull-up;
>> +};
>> +
>> +&qup_uart1_tx {
>> +	/* We'll drive TX, so no pull */
>> +	drive-strength = <2>;
>> +	bias-disable;
>> +};
>
> I recently made some changes to pincfg-node.yaml to detect if there's
> conflicting properties used, and these got detected. Should these not
> do what has been done on the msm8998-xiaomi-sagit, and delete the
> inherited bias-foo from the dtsi?
> &blsp1_i2c5_sleep {
> 	/delete-property/ bias-pull-up;
> 	bias-disable;
> };

Yes, you're completely right.

In the final dtb qup-uart1-{cts,rts,rx,tx}-default-state contain two
bias-* properties, this must be wrong.

Thanks for pointing this out, I'll prepare a patch soon!

Regards
Luca

Re: [PATCH v2 4/4] arm64: dts: qcom: sm7225-fairphone-fp4: Add Bluetooth

[Conor Dooley]

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On Wed, Mar 11, 2026 at 09:04:20AM +0100, Luca Weiss wrote:
> On Tue Mar 10, 2026 at 7:02 PM CET, Conor Dooley wrote:
> > On Fri, May 12, 2023 at 03:58:26PM +0200, Luca Weiss wrote:
> >
> >> +&qup_uart1_cts {
> >> +	/*
> >> +	 * Configure a bias-bus-hold on CTS to lower power
> >> +	 * usage when Bluetooth is turned off. Bus hold will
> >> +	 * maintain a low power state regardless of whether
> >> +	 * the Bluetooth module drives the pin in either
> >> +	 * direction or leaves the pin fully unpowered.
> >> +	 */
> >> +	bias-bus-hold;
> >> +};
> >> +
> >> +&qup_uart1_rts {
> >> +	/* We'll drive RTS, so no pull */
> >> +	drive-strength = <2>;
> >> +	bias-disable;
> >> +};
> >> +
> >> +&qup_uart1_rx {
> >> +	/*
> >> +	 * Configure a pull-up on RX. This is needed to avoid
> >> +	 * garbage data when the TX pin of the Bluetooth module is
> >> +	 * in tri-state (module powered off or not driving the
> >> +	 * signal yet).
> >> +	 */
> >> +	bias-pull-up;
> >> +};
> >> +
> >> +&qup_uart1_tx {
> >> +	/* We'll drive TX, so no pull */
> >> +	drive-strength = <2>;
> >> +	bias-disable;
> >> +};
> >
> > I recently made some changes to pincfg-node.yaml to detect if there's
> > conflicting properties used, and these got detected. Should these not
> > do what has been done on the msm8998-xiaomi-sagit, and delete the
> > inherited bias-foo from the dtsi?
> > &blsp1_i2c5_sleep {
> > 	/delete-property/ bias-pull-up;
> > 	bias-disable;
> > };
> 
> Yes, you're completely right.
> 
> In the final dtb qup-uart1-{cts,rts,rx,tx}-default-state contain two
> bias-* properties, this must be wrong.
> 
> Thanks for pointing this out, I'll prepare a patch soon!


Cool, guess it just worked for you because of either property ordering
or how linux parsed it.

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