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Commit c68f6e2e authored by Pali Rohár's avatar Pali Rohár Committed by Greg Kroah-Hartman
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serial: mvebu-uart: correctly report configured baudrate value 



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: 68a0db1d ("serial: mvebu-uart: add function to change baudrate")
Cc: stable <stable@kernel.org>
Reviewed-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: default avatarPali Rohár <pali@kernel.org>
Link: https://lore.kernel.org/r/20220628100922.10717-1-pali@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2230428f

drivers/tty/serial/mvebu-uart.c

+13 −12
Original line number Diff line number Diff line
@@ -443,13 +443,13 @@ static void mvebu_uart_shutdown(struct uart_port *port) 
	}

}



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:
@@ -473,7 +473,7 @@ static int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud) 
	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,
@@ -510,15 +510,11 @@ static void mvebu_uart_set_termios(struct uart_port *port, 
	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) {
@@ -529,6 +525,11 @@ static void mvebu_uart_set_termios(struct uart_port *port, 
		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);

}