From: Pali Rohár pali@kernel.org
commit 4f532c1e25319e42996ec18a1f473fd50c8e575d upstream.
Functions tty_termios_encode_baud_rate() and uart_update_timeout() should be called with the baudrate value which was set to hardware. Linux then report exact values via ioctl(TCGETS2) to userspace.
Change mvebu_uart_baud_rate_set() function to return baudrate value which was set to hardware and propagate this value to above mentioned functions.
With this change userspace would see precise value in termios c_ospeed field.
Fixes: 68a0db1d7da2 ("serial: mvebu-uart: add function to change baudrate") Cc: stable stable@kernel.org Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Signed-off-by: Pali Rohár pali@kernel.org Link: https://lore.kernel.org/r/20220628100922.10717-1-pali@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/serial/mvebu-uart.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-)
--- a/drivers/tty/serial/mvebu-uart.c +++ b/drivers/tty/serial/mvebu-uart.c @@ -442,13 +442,13 @@ static void mvebu_uart_shutdown(struct u } }
-static int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud) +static unsigned int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud) { unsigned int d_divisor, m_divisor; u32 brdv, osamp;
if (!port->uartclk) - return -EOPNOTSUPP; + return 0;
/* * The baudrate is derived from the UART clock thanks to two divisors: @@ -472,7 +472,7 @@ static int mvebu_uart_baud_rate_set(stru osamp &= ~OSAMP_DIVISORS_MASK; writel(osamp, port->membase + UART_OSAMP);
- return 0; + return DIV_ROUND_CLOSEST(port->uartclk, d_divisor * m_divisor); }
static void mvebu_uart_set_termios(struct uart_port *port, @@ -509,15 +509,11 @@ static void mvebu_uart_set_termios(struc max_baud = 230400;
baud = uart_get_baud_rate(port, termios, old, min_baud, max_baud); - if (mvebu_uart_baud_rate_set(port, baud)) { - /* No clock available, baudrate cannot be changed */ - if (old) - baud = uart_get_baud_rate(port, old, NULL, - min_baud, max_baud); - } else { - tty_termios_encode_baud_rate(termios, baud, baud); - uart_update_timeout(port, termios->c_cflag, baud); - } + baud = mvebu_uart_baud_rate_set(port, baud); + + /* In case baudrate cannot be changed, report previous old value */ + if (baud == 0 && old) + baud = tty_termios_baud_rate(old);
/* Only the following flag changes are supported */ if (old) { @@ -528,6 +524,11 @@ static void mvebu_uart_set_termios(struc termios->c_cflag |= CS8; }
+ if (baud != 0) { + tty_termios_encode_baud_rate(termios, baud, baud); + uart_update_timeout(port, termios->c_cflag, baud); + } + spin_unlock_irqrestore(&port->lock, flags); }