linux-kernel - Re: [PATCH v3] bluetooth: hci_qca: Fix qca6390 enable failure after warm reboot

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Message-ID: <20200527164832.GH4525@google.com>
Date:   Wed, 27 May 2020 09:48:32 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Zijun Hu <zijuhu@...eaurora.org>
Cc:     marcel@...tmann.org, johan.hedberg@...il.com,
        linux-kernel@...r.kernel.org, linux-bluetooth@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, bgodavar@...eaurora.org,
        c-hbandi@...eaurora.org, hemantg@...eaurora.org,
        rjliao@...eaurora.org
Subject: Re: [PATCH v3] bluetooth: hci_qca: Fix qca6390 enable failure after
 warm reboot

Hi Zijun,

On Wed, May 27, 2020 at 10:32:39AM +0800, Zijun Hu wrote:
> Warm reboot can not restore qca6390 controller baudrate
> to default due to lack of controllable BT_EN pin or power
> supply, so fails to download firmware after warm reboot.
> 
> Fixed by sending EDL_SOC_RESET VSC to reset controller
> within added device shutdown implementation.
> 
> Signed-off-by: Zijun Hu <zijuhu@...eaurora.org>
> ---
>  drivers/bluetooth/hci_qca.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index e4a6823..4b6f8b6 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -1975,6 +1975,34 @@ static void qca_serdev_remove(struct serdev_device *serdev)
>  	hci_uart_unregister_device(&qcadev->serdev_hu);
>  }
>  
> +static void qca_serdev_shutdown(struct device *dev)
> +{
> +	int ret;
> +	int timeout = msecs_to_jiffies(CMD_TRANS_TIMEOUT_MS);
> +	struct serdev_device *serdev = to_serdev_device(dev);
> +	struct qca_serdev *qcadev = serdev_device_get_drvdata(serdev);
> +	const u8 ibs_wake_cmd[] = { 0xFD };
> +	const u8 edl_reset_soc_cmd[] = { 0x01, 0x00, 0xFC, 0x01, 0x05 };
> +
> +	if (qcadev->btsoc_type == QCA_QCA6390) {
> +		serdev_device_write_flush(serdev);
> +		serdev_device_write_buf(serdev,
> +				ibs_wake_cmd, sizeof(ibs_wake_cmd));
> +		serdev_device_wait_until_sent(serdev, timeout);

Why no check of the return value of serdev_device_write_buf() here,
does it make sense to continue if sending the wakeup command failed?

Couldn't serdev_device_write() be used instead of the _write_buf() +
_wait_until_sent() combo?

> +		usleep_range(8000, 10000);
> +
> +		serdev_device_write_flush(serdev);

I suppose the flush is done because _wait_until_sent() could have timed out.
Another reason to use _device_write() (if suitable), since it returns
-ETIMEDOUT in that case?

> +		ret = serdev_device_write_buf(serdev,
> +				edl_reset_soc_cmd, sizeof(edl_reset_soc_cmd));
> +		if (ret < 0) {
> +			BT_ERR("QCA send EDL_RESET_REQ error: %d", ret);
> +			return;
> +		}
> +		serdev_device_wait_until_sent(serdev, timeout);
> +		usleep_range(8000, 10000);
> +	}
> +}
> +
>  static int __maybe_unused qca_suspend(struct device *dev)
>  {
>  	struct hci_dev *hdev = container_of(dev, struct hci_dev, dev);
> @@ -2100,6 +2128,7 @@ static struct serdev_device_driver qca_serdev_driver = {
>  		.name = "hci_uart_qca",
>  		.of_match_table = of_match_ptr(qca_bluetooth_of_match),
>  		.acpi_match_table = ACPI_PTR(qca_bluetooth_acpi_match),
> +		.shutdown = qca_serdev_shutdown,
>  		.pm = &qca_pm_ops,
>  	},
>  };
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
>