On Sat 19 Oct 15:12 PDT 2019, Jeffrey Hugo wrote:
> It turns out that the wcn3990 can float the gpio lines during bootup, etc
> which will result in the uart core thinking there is incoming data. This
> results in the bluetooth stack getting garbage. By applying a bias to
> match what wcn3990 would drive, the issue is corrected.
>
> Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@xxxxxxxxx>
> ---
> .../boot/dts/qcom/msm8998-clamshell.dtsi | 31 +++++++++++++++++++
> arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi | 31 +++++++++++++++++++
> 2 files changed, 62 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi b/arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi
> index ab24d415acc0..7e02cb6c8e07 100644
> --- a/arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi
> +++ b/arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi
> @@ -74,6 +74,37 @@
> };
> };
>
> +&blsp1_uart3_on {
> + /delete-node/ config;
So it would make much more sense then to split &blsp1_uart3_on in
sections defining its pins, than the "logical" config and mux split.
Please send a patch that changes msm8998-pins.dtsi to be:
blsp_uart3_on: blsp1-uart3-on {
ctx {
};
rts {
};
rx [
};
tx {
};
};
There's no need for the "pinconf" part and for pinctrl states with a
single pin/group we can simply omit the subnode (as this is now
possible).
Apart from that, I think this looks good!
Regards,
Bjorn
> +
> + pinconf-cts {
> + /*
> + * Configure a pull-down on 47 (CTS) to match the pull
> + * of the Bluetooth module.
> + */
> + pins = "gpio47";
> + bias-pull-down;
> + };
> +
> + pinconf-rts-tx {
> + /* We'll drive 48 (RFR) and 45 (TX), so no pull */
> + pins = "gpio45", "gpio48";
> + drive-strength = <2>;
> + bias-disable;
> + };
> +
> + pinconf-rx {
> + /*
> + * Configure a pull-up on 45 (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).
> + */
> + pins = "gpio45";
> + bias-pull-up;
> + };
> +};
> +
> &dsi0 {
> status = "okay";
>
> diff --git a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
> index 1a1836ed1052..17f51af5e999 100644
> --- a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
> +++ b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
> @@ -37,6 +37,37 @@
> };
> };
>
> +&blsp1_uart3_on {
> + /delete-node/ config;
> +
> + pinconf-cts {
> + /*
> + * Configure a pull-down on 47 (CTS) to match the pull
> + * of the Bluetooth module.
> + */
> + pins = "gpio47";
> + bias-pull-down;
> + };
> +
> + pinconf-rts-tx {
> + /* We'll drive 48 (RFR) and 45 (TX), so no pull */
> + pins = "gpio45", "gpio48";
> + drive-strength = <2>;
> + bias-disable;
> + };
> +
> + pinconf-rx {
> + /*
> + * Configure a pull-up on 45 (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).
> + */
> + pins = "gpio45";
> + bias-pull-up;
> + };
> +};
> +
> &blsp2_uart1 {
> status = "okay";
> };
> --
> 2.17.1
>
