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charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.2 (2019-09-21) Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Tue, Mar 17, 2020 at 05:18:34PM +0530, Akash Asthana wrote: > Hi Matthias, > > On 3/14/2020 2:58 AM, Matthias Kaehlcke wrote: > > Hi Akash, > > > > On Fri, Mar 13, 2020 at 06:42:10PM +0530, Akash Asthana wrote: > > > Get the interconnect paths for Uart based Serial Engine device > > > and vote according to the baud rate requirement of the driver. > > > > > > Signed-off-by: Akash Asthana > > > --- > > > Changes in V2: > > > - As per Bjorn's comment, removed se == NULL check from geni_serial_icc_get > > > - As per Bjorn's comment, removed code to set se->icc_path* to NULL in failure > > > - As per Bjorn's comment, introduced and using devm_of_icc_get API for getting > > > path handle > > > - As per Matthias comment, added error handling for icc_set_bw call > > > > > > drivers/tty/serial/qcom_geni_serial.c | 69 +++++++++++++++++++++++++++++++++-- > > > 1 file changed, 65 insertions(+), 4 deletions(-) > > > > > > diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c > > > index 272bae0..c8ad7e9 100644 > > > --- a/drivers/tty/serial/qcom_geni_serial.c > > > +++ b/drivers/tty/serial/qcom_geni_serial.c > > > > > > ... > > > > > > static int qcom_geni_serial_request_port(struct uart_port *uport) > > > { > > > struct platform_device *pdev = to_platform_device(uport->dev); > > > @@ -962,6 +975,7 @@ static void qcom_geni_serial_set_termios(struct uart_port *uport, > > > struct qcom_geni_serial_port *port = to_dev_port(uport, uport); > > > unsigned long clk_rate; > > > u32 ver, sampling_rate; > > > + int ret; > > > qcom_geni_serial_stop_rx(uport); > > > /* baud rate */ > > > @@ -983,6 +997,18 @@ static void qcom_geni_serial_set_termios(struct uart_port *uport, > > > ser_clk_cfg = SER_CLK_EN; > > > ser_clk_cfg |= clk_div << CLK_DIV_SHFT; > > > + /* > > > + * Put BW vote only on CPU path as driver supports FIFO mode only. > > > + * Assume peak_bw as twice of avg_bw. > > > + */ > > > + port->se.avg_bw_cpu = Bps_to_icc(baud); > > > + port->se.peak_bw_cpu = Bps_to_icc(2 * baud); > > > + ret = icc_set_bw(port->se.icc_path_cpu_to_geni, port->se.avg_bw_cpu, > > > + port->se.peak_bw_cpu); > > > + if (ret) > > > + dev_err(uport->dev, "%s: ICC BW voting failed for cpu\n", > > > + __func__); > > Should this return an error? The port might not operate properly if the ICC > > bandwidth couldn't be configured > > This is void function we can't return error from here. I guess it would be > somewhat okay if BW voting failed for CPU path but clk_set_rate failure is > more serious which is called from this function, I don't think it can be > move to somewhere else. ok, I missed that _set_termios() is void. > > > static const struct uart_ops qcom_geni_console_pops = { > > > @@ -1308,6 +1358,17 @@ static int qcom_geni_serial_probe(struct platform_device *pdev) > > > port->rx_fifo_depth = DEF_FIFO_DEPTH_WORDS; > > > port->tx_fifo_width = DEF_FIFO_WIDTH_BITS; > > > + ret = geni_serial_icc_get(&port->se); > > > + if (ret) > > > + return ret; > > > + /* Set the bus quota to a reasonable value */ > > > + port->se.avg_bw_core = console ? Bps_to_icc(1000) : > > > + Bps_to_icc(CORE_2X_50_MHZ); > > Why different settings for console vs. non-console? > > QUP FW runs on core clock. To support higher throughput we want FW to run at > higher speed. > > Since Console operate at 115200bps and BT operate at 3.2Mbps baud. We are > voting higher on core for BT usecase. > > These value are recommended from HW team. IIUC none of the values you mention are set in stone. 115200bps seems to be a 'standard' value for the serial console, but it could be a different baudrate. I guess you are referring to Qualcomm Bluetooth controllers, which are only one of many things that could be connected to the port. And what happens when a QCA BT controller is connected to a non-geni/QCA port, which doesn't know about its 'requirements'? The answer is that both the BT controller and the serial console configure the baudrate they need, hence using different values in _probe() is pointless. Unsurprisingly one of the first things the QCA BT driver does is to configure the baudrate. It typically starts with a lower ('init') speed, and then switches to the higher ('operational') baudrate: https://elixir.bootlin.com/linux/v5.5.8/source/drivers/bluetooth/hci_qca.c#L1256