From mboxrd@z Thu Jan 1 00:00:00 1970 From: Balakrishna Godavarthi Subject: Re: [PATCH v1 2/4] Bluetooth: hci_qca: Pull RTS line high for baudrate change command Date: Wed, 14 Nov 2018 12:02:16 +0530 Message-ID: <25c29e35b32ca71fe6d0b02f4d6ed559@codeaurora.org> References: <20181106120528.30342-1-bgodavar@codeaurora.org> <20181106120528.30342-3-bgodavar@codeaurora.org> <20181114015504.GH22824@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20181114015504.GH22824@google.com> Sender: linux-kernel-owner@vger.kernel.org To: Matthias Kaehlcke Cc: marcel@holtmann.org, johan.hedberg@gmail.com, 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 2018-11-14 07:25, Matthias Kaehlcke wrote: > On Tue, Nov 06, 2018 at 05:35:26PM +0530, Balakrishna Godavarthi wrote: >> This patch will pull the RTS line high instead of turning off the >> flow control, while changing baudrate of host and chip. > > Please don't only describe what is changed, but also why this change > is necessary. > > IIUC the BT chip honors flow control during baudrate changes, however > it sometimes sends 'garbage' which results in "Bluetooth: hci0: Frame > reassembly failed (-84)" messages. > [Bala]: will update the commit text. >> Signed-off-by: Balakrishna Godavarthi >> --- >> 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 051f081d1835..8301663f0004 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; >> >> + /* Pulling RTS line to high is mandatory while sending change >> + * baudrate request to SoC and also while setting the host >> + * baudrate. >> + */ > > Instead of just stating that this is 'mandatory' explain why it is > needed. Also better say 'Deassert RTS' instead of the more lower level > 'Pulling RTS line to high'. It could be something like 'Deassert RTS > to prevent the BT controller from sending garbage during the baudrate > change.' > [Bala]: will update the comment. >> + 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; > > Tested-by: Matthias Kaehlcke Thanks for testing. -- Regards Balakrishna.