From ce734600545fc7da8ae2c5d192b255761a244fb3 Mon Sep 17 00:00:00 2001 From: Vivek Gautam Date: Thu, 1 Aug 2019 17:41:53 +0530 Subject: [PATCH] tty: serial: qcom_geni_serial: Update the oversampling rate For QUP IP versions 2.5 and above the oversampling rate is halved from 32 to 16. Update this rate after reading hardware version register, so that the clock divider value is correctly set to achieve required baud rate. Signed-off-by: Vivek Gautam Link: https://lore.kernel.org/r/20190801121153.10613-1-vivek.gautam@codeaurora.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/qcom_geni_serial.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c index f879710..c73c183 100644 --- a/drivers/tty/serial/qcom_geni_serial.c +++ b/drivers/tty/serial/qcom_geni_serial.c @@ -920,12 +920,13 @@ static unsigned long get_clk_cfg(unsigned long clk_freq) return 0; } -static unsigned long get_clk_div_rate(unsigned int baud, unsigned int *clk_div) +static unsigned long get_clk_div_rate(unsigned int baud, + unsigned int sampling_rate, unsigned int *clk_div) { unsigned long ser_clk; unsigned long desired_clk; - desired_clk = baud * UART_OVERSAMPLING; + desired_clk = baud * sampling_rate; ser_clk = get_clk_cfg(desired_clk); if (!ser_clk) { pr_err("%s: Can't find matching DFS entry for baud %d\n", @@ -951,12 +952,20 @@ static void qcom_geni_serial_set_termios(struct uart_port *uport, u32 ser_clk_cfg; struct qcom_geni_serial_port *port = to_dev_port(uport, uport); unsigned long clk_rate; + u32 ver, sampling_rate; qcom_geni_serial_stop_rx(uport); /* baud rate */ baud = uart_get_baud_rate(uport, termios, old, 300, 4000000); port->baud = baud; - clk_rate = get_clk_div_rate(baud, &clk_div); + + sampling_rate = UART_OVERSAMPLING; + /* Sampling rate is halved for IP versions >= 2.5 */ + ver = geni_se_get_qup_hw_version(&port->se); + if (GENI_SE_VERSION_MAJOR(ver) >= 2 && GENI_SE_VERSION_MINOR(ver) >= 5) + sampling_rate /= 2; + + clk_rate = get_clk_div_rate(baud, sampling_rate, &clk_div); if (!clk_rate) goto out_restart_rx; -- 2.7.4