@@ -481,7 +481,7 @@ static void mvebu_uart_set_termios(struct uart_port *port,
struct ktermios *old)
{
unsigned long flags;
- unsigned int baud;
+ unsigned int baud, min_baud, max_baud;
spin_lock_irqsave(&port->lock, flags);
@@ -500,16 +500,21 @@ static void mvebu_uart_set_termios(struct uart_port *port,
port->ignore_status_mask |= STAT_RX_RDY(port) | STAT_BRK_ERR;
/*
+ * Maximal divisor is 1023 * 16 when using default (x16) scheme.
* Maximum achievable frequency with simple baudrate divisor is 230400.
* Since the error per bit frame would be of more than 15%, achieving
* higher frequencies would require to implement the fractional divisor
* feature.
*/
- baud = uart_get_baud_rate(port, termios, old, 0, 230400);
+ min_baud = DIV_ROUND_UP(port->uartclk, 1023 * 16);
+ 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, 0, 230400);
+ 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);
For default (x16) scheme which is currently used by mvebu-uart.c driver, maximal divisor of UART base clock is 1023*16. Therefore there is limit for minimal supported baudrate. This change calculate it correctly and prevents setting invalid divisor 0 into hardware registers. Signed-off-by: Pali Rohár <pali@kernel.org> Fixes: 68a0db1d7da2 ("serial: mvebu-uart: add function to change baudrate") --- drivers/tty/serial/mvebu-uart.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)