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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: 68a0db1d7d ("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>
This commit is contained in:
Pali Rohár 2021-06-25 00:49:01 +02:00 committed by Greg Kroah-Hartman
parent 44d36a79dc
commit 7900c98108
1 changed files with 2 additions and 3 deletions
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5
drivers/tty/serial/mvebu-uart.c
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@ -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: