serial: mvebu-uart: do not allow changing baudrate when uartclk is not available

[ Upstream commit ecd6b010d81f97b06b2f64d2d4f50ebf5acddaa9 ]

Testing mvuart->clk for non-error is not enough as mvuart->clk may contain
valid clk pointer but when clk_prepare_enable(mvuart->clk) failed then
port->uartclk is zero.

When mvuart->clk is not available then port->uartclk is zero too.

Parent clock rate port->uartclk is needed to calculate UART clock divisor
and without it is not possible to change baudrate.

So fix test condition when it is possible to change baudrate.

Signed-off-by: Pali Rohár <pali@kernel.org>
Fixes: 68a0db1d7da2 ("serial: mvebu-uart: add function to change baudrate")
Link: https://lore.kernel.org/r/20210624224909.6350-3-pali@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/tty/serial/mvebu-uart.c b/drivers/tty/serial/mvebu-uart.c
index 908a4ac6b5a7accf38f3b3fd1d96ed7fbac68365..9638ae6aae7952609a02d6b5ce779b74efbf1104 100644 (file)
--- a/drivers/tty/serial/mvebu-uart.c
+++ b/drivers/tty/serial/mvebu-uart.c
@@ -445,12 +445,11 @@ static void mvebu_uart_shutdown(struct uart_port *port)
 
 static int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud)
 {
-       struct mvebu_uart *mvuart = to_mvuart(port);
        unsigned int d_divisor, m_divisor;
        u32 brdv, osamp;
 
-       if (IS_ERR(mvuart->clk))
-               return -PTR_ERR(mvuart->clk);
+       if (!port->uartclk)
+               return -EOPNOTSUPP;
 
        /*
         * The baudrate is derived from the UART clock thanks to two divisors: