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    Subject[PATCH v2 2/3] Bluetooth: hci_qca: Deassert RTS while baudrate change command
    Date
    This patch will help to stop frame reassembly errors while changing
    the baudrate. This is because host send a change baudrate request
    command to the chip with 115200 bps, Whereas chip will change their
    UART clocks to the enable for new baudrate and sends the response
    for the change request command with newer baudrate, On host side
    we are still operating in 115200 bps which results of reading garbage
    data. Here we are pulling RTS line, so that chip we will wait to send data
    to host until host change its baudrate.

    Signed-off-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
    Tested-by: Matthias Kaehlcke <mka@chromium.org>
    ---
    v2:
    * updated commit text and comments.
    v1:
    * initial patch
    ---
    drivers/bluetooth/hci_qca.c | 23 ++++++++++++-----------
    1 file changed, 12 insertions(+), 11 deletions(-)

    diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
    index f5dd323c1967..ed905ea1c58a 100644
    --- a/drivers/bluetooth/hci_qca.c
    +++ b/drivers/bluetooth/hci_qca.c
    @@ -963,7 +963,6 @@ static int qca_set_baudrate(struct hci_dev *hdev, uint8_t baudrate)
    struct hci_uart *hu = hci_get_drvdata(hdev);
    struct qca_data *qca = hu->priv;
    struct sk_buff *skb;
    - struct qca_serdev *qcadev;
    u8 cmd[] = { 0x01, 0x48, 0xFC, 0x01, 0x00 };

    if (baudrate > QCA_BAUDRATE_3200000)
    @@ -977,13 +976,6 @@ static int qca_set_baudrate(struct hci_dev *hdev, uint8_t baudrate)
    return -ENOMEM;
    }

    - /* Disabling hardware flow control is mandatory while
    - * sending change baudrate request to wcn3990 SoC.
    - */
    - qcadev = serdev_device_get_drvdata(hu->serdev);
    - if (qcadev->btsoc_type == QCA_WCN3990)
    - hci_uart_set_flow_control(hu, true);
    -
    /* Assign commands to change baudrate and packet type. */
    skb_put_data(skb, cmd, sizeof(cmd));
    hci_skb_pkt_type(skb) = HCI_COMMAND_PKT;
    @@ -999,9 +991,6 @@ static int qca_set_baudrate(struct hci_dev *hdev, uint8_t baudrate)
    schedule_timeout(msecs_to_jiffies(BAUDRATE_SETTLE_TIMEOUT_MS));
    set_current_state(TASK_RUNNING);

    - if (qcadev->btsoc_type == QCA_WCN3990)
    - hci_uart_set_flow_control(hu, false);
    -
    return 0;
    }

    @@ -1086,6 +1075,7 @@ static int qca_check_speeds(struct hci_uart *hu)
    static int qca_set_speed(struct hci_uart *hu, enum qca_speed_type speed_type)
    {
    unsigned int speed, qca_baudrate;
    + struct qca_serdev *qcadev;
    int ret;

    if (speed_type == QCA_INIT_SPEED) {
    @@ -1097,6 +1087,14 @@ static int qca_set_speed(struct hci_uart *hu, enum qca_speed_type speed_type)
    if (!speed)
    return 0;

    + /* Deassert RTS while changing the baudrate of chip and host.
    + * This will stop chip to transmit it response with an newer
    + * baudrate until we change the baudarte.
    + */
    + qcadev = serdev_device_get_drvdata(hu->serdev);
    + if (qcadev->btsoc_type == QCA_WCN3990)
    + serdev_device_set_rts(hu->serdev, false);
    +
    qca_baudrate = qca_get_baudrate_value(speed);
    bt_dev_dbg(hu->hdev, "Set UART speed to %d", speed);
    ret = qca_set_baudrate(hu->hdev, qca_baudrate);
    @@ -1104,6 +1102,9 @@ static int qca_set_speed(struct hci_uart *hu, enum qca_speed_type speed_type)
    return ret;

    host_set_baudrate(hu, speed);
    +
    + if (qcadev->btsoc_type == QCA_WCN3990)
    + serdev_device_set_rts(hu->serdev, true);
    }

    return 0;
    --
    The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
    a Linux Foundation Collaborative Project
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