From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthias Kaehlcke Subject: Re: [PATCH v5 2/5] Bluetooth: hci_qca: Deassert RTS while baudrate change command Date: Fri, 18 Jan 2019 16:31:09 -0800 Message-ID: <20190119003109.GD261387@google.com> References: <20190110143928.GE3430@localhost> <61301df80bd6a8ee0265b31b7f6a3aa1@codeaurora.org> <20190111013707.GD261387@google.com> <194b5d18ea86830b6a24939d483a964c@codeaurora.org> <20190111235633.GK261387@google.com> <20190115234628.GQ261387@google.com> <20190117160944.GV3691@localhost> <20190117172109.GU261387@google.com> <20190118094416.GB3691@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Content-Disposition: inline In-Reply-To: <20190118094416.GB3691@localhost> Sender: linux-kernel-owner@vger.kernel.org To: Johan Hovold Cc: Balakrishna Godavarthi , 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, Johan Hovold List-Id: linux-arm-msm@vger.kernel.org On Fri, Jan 18, 2019 at 10:44:16AM +0100, Johan Hovold wrote: > On Thu, Jan 17, 2019 at 09:21:09AM -0800, Matthias Kaehlcke wrote: > > > I observed that the qcom_geni_serial driver doesn't raise RTS with > > flow control disabled. It seems we have to investigate why that's the > > case. I agree that the driver should be platform agnostic. > > Sounds like a driver bug, unless the hardware is just "odd". The > driver implementation of this looks very non-standard judging from a > quick peek. > > In fact, qcom_geni_serial_get_mctrl() is currently a no-op if hardware > flow control is not enabled: > > if (uart_console(uport) || !uart_cts_enabled(uport)) > return; > > Perhaps dropping the !uart_cts_enabled() test is sufficient. Thanks for taking a look Johan, that was indeed the problem (also in set_mctrl()). I posted a fix: https://lore.kernel.org/patchwork/patch/1033611/ Balakrishna, the following (applied on top of your patch) works for me with the UART patch above: diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c index 9d5e41f159c78f..60bfdf01f72841 100644 --- a/drivers/bluetooth/hci_qca.c +++ b/drivers/bluetooth/hci_qca.c @@ -1080,7 +1080,7 @@ 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; + int ret = 0; if (speed_type == QCA_INIT_SPEED) { speed = qca_get_speed(hu, QCA_INIT_SPEED); @@ -1097,22 +1097,27 @@ static int qca_set_speed(struct hci_uart *hu, enum qca_speed_type speed_type) * the old speed. */ qcadev = serdev_device_get_drvdata(hu->serdev); - if (qcadev->btsoc_type == QCA_WCN3990) + if (qcadev->btsoc_type == QCA_WCN3990) { + hci_uart_set_flow_control(hu, true); 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); if (ret) - return ret; + goto out; host_set_baudrate(hu, speed); - if (qcadev->btsoc_type == QCA_WCN3990) +out: + if (qcadev->btsoc_type == QCA_WCN3990) { + hci_uart_set_flow_control(hu, false); serdev_device_set_rts(hu->serdev, true); + } } - return 0; + return ret; } static int qca_wcn3990_init(struct hci_uart *hu)