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Date:   Thu, 12 Dec 2019 09:43:48 -0800
From:   Matthias Kaehlcke <mka@chromium.org>
To:     Balakrishna Godavarthi <bgodavar@codeaurora.org>
Cc:     marcel@holtmann.org, johan.hedberg@gmail.com,
        linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org,
        hemantg@codeaurora.org, linux-arm-msm@vger.kernel.org,
        tientzu@chromium.org, seanpaul@chromium.org
Subject: Re: [PATCH v1] Bluetooth: hci_qca: Enable clocks required for BT SOC
Message-ID: <20191212174348.GS228856@google.com>
References: <20191114081430.25427-1-bgodavar@codeaurora.org>
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Sender: linux-bluetooth-owner@vger.kernel.org
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On Thu, Nov 14, 2019 at 01:44:30PM +0530, Balakrishna Godavarthi wrote:
> Instead of relying on other subsytem to turn ON clocks
> required for BT SoC to operate, voting them from the driver.
> 
> Signed-off-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
> ---
>  drivers/bluetooth/hci_qca.c | 31 +++++++++++++++++++++++++++++--
>  1 file changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index f10bdf8e1fc5..dc95e378574b 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -164,6 +164,7 @@ struct qca_serdev {
>  };
>  
>  static int qca_regulator_enable(struct qca_serdev *qcadev);
> +static int qca_power_on(struct qca_serdev *qcadev);
>  static void qca_regulator_disable(struct qca_serdev *qcadev);
>  static void qca_power_shutdown(struct hci_uart *hu);
>  static int qca_power_off(struct hci_dev *hdev);
> @@ -528,7 +529,7 @@ static int qca_open(struct hci_uart *hu)
>  		} else {
>  			hu->init_speed = qcadev->init_speed;
>  			hu->oper_speed = qcadev->oper_speed;
> -			ret = qca_regulator_enable(qcadev);
> +			ret = qca_power_on(qcadev);
>  			if (ret) {
>  				destroy_workqueue(qca->workqueue);
>  				kfree_skb(qca->rx_skb);
> @@ -1214,7 +1215,7 @@ static int qca_wcn3990_init(struct hci_uart *hu)
>  	qcadev = serdev_device_get_drvdata(hu->serdev);
>  	if (!qcadev->bt_power->vregs_on) {
>  		serdev_device_close(hu->serdev);
> -		ret = qca_regulator_enable(qcadev);
> +		ret = qca_power_on(qcadev);
>  		if (ret)
>  			return ret;
>  
> @@ -1408,6 +1409,9 @@ static void qca_power_shutdown(struct hci_uart *hu)
>  	host_set_baudrate(hu, 2400);
>  	qca_send_power_pulse(hu, false);
>  	qca_regulator_disable(qcadev);
> +
> +	if (qcadev->susclk)
> +		clk_disable_unprepare(qcadev->susclk);
>  }
>  
>  static int qca_power_off(struct hci_dev *hdev)
> @@ -1423,6 +1427,20 @@ static int qca_power_off(struct hci_dev *hdev)
>  	return 0;
>  }
>  
> +static int qca_power_on(struct qca_serdev *qcadev)
> +{
> +	int err;
> +
> +	if (qcadev->susclk) {
> +		err = clk_prepare_enable(qcadev->susclk);
> +		if (err)
> +			return err;
> +	}
> +
> +	qca_regulator_enable(qcadev);
> +	return 0;
> +}
> +
>  static int qca_regulator_enable(struct qca_serdev *qcadev)
>  {
>  	struct qca_power *power = qcadev->bt_power;
> @@ -1523,6 +1541,15 @@ static int qca_serdev_probe(struct serdev_device *serdev)
>  
>  		qcadev->bt_power->vregs_on = false;
>  
> +		if (qcadev->btsoc_type == QCA_WCN3990 ||
> +		    qcadev->btsoc_type == QCA_WCN3991) {
> +			qcadev->susclk = devm_clk_get(&serdev->dev, NULL);
> +			if (IS_ERR(qcadev->susclk)) {
> +				dev_err(&serdev->dev, "failed to acquire clk\n");
> +				return PTR_ERR(qcadev->susclk);
> +			}

This will break existing users. Use devm_clk_get_optional() and at most
raise a warning if the clock doesn't exist.

It would also be nice to add the clock to the affected devices in the tree
if possible:

arch/arm64/boot/dts/qcom/msm8998-clamshell.dtsi:                compatible = "qcom,wcn3990-bt";
arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi:              compatible = "qcom,wcn3990-bt";
arch/arm64/boot/dts/qcom/qcs404-evb.dtsi:               compatible = "qcom,wcn3990-bt";
arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi:             compatible = "qcom,wcn3990-bt";
arch/arm64/boot/dts/qcom/sdm845-db845c.dts:             compatible = "qcom,wcn3990-bt";
arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts:           compatible = "qcom,wcn3990-bt";