From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthias Kaehlcke Subject: Re: [PATCH v9 2/3] Bluetooth: hci_qca: Deassert RTS while baudrate change command Date: Thu, 24 Jan 2019 16:12:59 -0800 Message-ID: <20190125001259.GB81583@google.com> References: <20190124120808.8275-1-bgodavar@codeaurora.org> <20190124120808.8275-3-bgodavar@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Content-Disposition: inline In-Reply-To: <20190124120808.8275-3-bgodavar@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org To: Balakrishna Godavarthi Cc: marcel@holtmann.org, johan.hedberg@gmail.com, johan@kernel.org, linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org, hemantg@codeaurora.org, linux-arm-msm@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org Hi Balakrishna, On Thu, Jan 24, 2019 at 05:38:07PM +0530, Balakrishna Godavarthi wrote: > 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 > Tested-by: Matthias Kaehlcke > Reviewed-by: Matthias Kaehlcke > --- > Changes in v9: > * disabled flow control while setting the baudrate of HOST and chip. > --- > drivers/bluetooth/hci_qca.c | 24 +++++++++++++----------- > 1 file changed, 13 insertions(+), 11 deletions(-) > > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c > index c08f4d105e73..6b5bcd44e24c 100644 > --- a/drivers/bluetooth/hci_qca.c > +++ b/drivers/bluetooth/hci_qca.c > @@ -964,7 +964,6 @@ 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) > @@ -978,13 +977,6 @@ 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; > @@ -1000,9 +992,6 @@ 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; > } > > @@ -1089,6 +1078,7 @@ 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) { > @@ -1100,6 +1090,15 @@ 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 prevent chip from transmitting its response with > + * the new baudrate while the host port is still operating at > + * the old speed. > + */ It is not necessarily evident which action deasserts RTS, I suggest to rephrase it to something like: "Disable flow control for wcn3990 to deassert RTS while ... " > + qcadev = serdev_device_get_drvdata(hu->serdev); > + if (qcadev->btsoc_type == QCA_WCN3990) > + hci_uart_set_flow_control(hu, true); > + > 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); flow control should be re-enabled in the error path. Cheers Matthias