[PATCH v1 4/4] arm64: dts: imx8mq-librem5: Set BQ25895 input voltage limit

[Sebastian Krzyszkowiak]

On niedziela, 27 września 2026 16:55:38 czas środkowoeuropejski letni Vincent 
Cloutier wrote:
> From: Vincent Cloutier <vincent at cloutier.co>
> 
> Purism's production Librem 5 kernels used a 3.9 V absolute VINDPM
> threshold for years,

...because it was (likely accidentally) left over from the devkit dts where it 
was genuinely needed.

> from the 2019 board support through the releases
> preceding the March 2026 charging update.

...which is when it was changed because it was found to be the cause of issues 
due to interactions between TPS65982 and BQ25895 cut-off limits observed when 
used with power sources that struggle to provide the required voltage when 
under load.

> Use this established board
> setting for the BQ25895 input voltage limit.

Why? What makes you want to bring the bad value upstream?

> Set input-voltage-limit-microvolt to 3900000 to select absolute VINDPM
> and program the 3.9 V threshold through the generic binding.
> 
> Tested on Librem 5r4: REG0D remained 0x8d across an attached boot, unplug,
> and flipped replug.
> 
> Assisted-by: OpenCode:gpt-5.6-sol
> Assisted-by: OpenCode:gpt-6-astra
> Signed-off-by: Vincent Cloutier <vincent at cloutier.co>
> ---
>  arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi
> b/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi index
> 099195279e84..8badebfcdbb4 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi
> @@ -1195,6 +1195,7 @@ bq25895: charger at 6a {
>  		pinctrl-0 = <&pinctrl_charger_in>;
>  		interrupt-parent = <&gpio3>;
>  		interrupts = <3 IRQ_TYPE_EDGE_FALLING>;
> +		input-voltage-limit-microvolt = <3900000>;
>  		ti,battery-regulation-voltage = <4208000>; /* uV */
>  		ti,termination-current = <128000>;  /* uA */
>  		ti,precharge-current = <128000>; /* uA */

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