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Date:   Wed, 15 Jan 2020 09:33:15 -0800
From:   Matthias Kaehlcke <mka@chromium.org>
To:     Rocky Liao <rjliao@codeaurora.org>
Cc:     marcel@holtmann.org, johan.hedberg@gmail.com,
        linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org,
        linux-arm-msm@vger.kernel.org, bgodavar@codeaurora.org,
        hemantg@codeaurora.org
Subject: Re: [PATCH v4 2/3] Bluetooth: hci_qca: Retry btsoc initialize when
 it fails
Message-ID: <20200115173315.GN89495@google.com>
References: <20191225060317.5258-1-rjliao@codeaurora.org>
 <20200115085552.11483-1-rjliao@codeaurora.org>
 <20200115085552.11483-2-rjliao@codeaurora.org>
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On Wed, Jan 15, 2020 at 04:55:51PM +0800, Rocky Liao wrote:
> This patch adds the retry of btsoc initialization when it fails. There are
> reports that the btsoc initialization may fail on some platforms but the
> repro ratio is very low. The symptoms is the firmware downloading failed
> due to the UART write timed out. The failure may be caused by UART,
> platform HW or the btsoc itself but it's very difficlut to root cause,
> given the repro ratio is very low. Add a retry for the btsoc initialization
> can work around most of the failures and make Bluetooth finally works.
> 
> Signed-off-by: Rocky Liao <rjliao@codeaurora.org>
> ---
> 
> Changes in v2: None
> Changes in v3: None
> Changes in v4:
>   -rebased the patch with latet code
>   -refined macro and variable name
>   -updated commit message
> 
>  drivers/bluetooth/hci_qca.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index ecb74965be10..1139142e8eed 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -55,6 +55,9 @@
>  /* Controller debug log header */
>  #define QCA_DEBUG_HANDLE	0x2EDC
>  
> +/* max retry count when init fails */
> +#define MAX_INIT_RETRIES 3
> +
>  /* Controller dump header */
>  #define QCA_SSR_DUMP_HANDLE		0x0108
>  #define QCA_DUMP_PACKET_SIZE		255
> @@ -1539,6 +1542,7 @@ static int qca_setup(struct hci_uart *hu)
>  	struct hci_dev *hdev = hu->hdev;
>  	struct qca_data *qca = hu->priv;
>  	unsigned int speed, qca_baudrate = QCA_BAUDRATE_115200;
> +	unsigned int retries = 0;
>  	enum qca_btsoc_type soc_type = qca_soc_type(hu);
>  	const char *firmware_name = qca_get_firmware_name(hu);
>  	int ret;
> @@ -1559,6 +1563,7 @@ static int qca_setup(struct hci_uart *hu)
>  	bt_dev_info(hdev, "setting up %s",
>  		qca_is_wcn399x(soc_type) ? "wcn399x" : "ROME");
>  
> +retry:
>  	ret = qca_power_on(hdev);
>  	if (ret)
>  		return ret;
> @@ -1613,6 +1618,20 @@ static int qca_setup(struct hci_uart *hu)
>  		 * patch/nvm-config is found, so run with original fw/config.
>  		 */
>  		ret = 0;
> +	} else {
> +		if (retries < MAX_INIT_RETRIES) {
> +			qca_power_shutdown(hu);
> +			if (hu->serdev) {
> +				serdev_device_close(hu->serdev);
> +				ret = serdev_device_open(hu->serdev);
> +				if (ret) {
> +					bt_dev_err(hdev, "failed to open port");
> +					return ret;
> +				}
> +			}
> +			retries++;
> +			goto retry;
> +		}
>  	}
>  
>  	/* Setup bdaddr */
> -- 

Assuming that this is really a rare condition:

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>