From mboxrd@z Thu Jan 1 00:00:00 1970 From: Balakrishna Godavarthi Subject: Re: [PATCH v9 2/3] Bluetooth: hci_qca: Deassert RTS while baudrate change command Date: Mon, 28 Jan 2019 19:15:48 +0530 Message-ID: <6b18e30fb1b747d674a75cb265b5821b@codeaurora.org> References: <20190124120808.8275-1-bgodavar@codeaurora.org> <20190124120808.8275-3-bgodavar@codeaurora.org> <20190125001259.GB81583@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190125001259.GB81583@google.com> Sender: linux-kernel-owner@vger.kernel.org To: Matthias Kaehlcke 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 Matthias, On 2019-01-25 05:42, Matthias Kaehlcke wrote: > 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 ... " > [Bala]: will update. >> + 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 [Bala; will update. -- Regards Balakrishna.