From: "Pali Rohár" <pali@kernel.org>
To: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Jiri Slaby" <jirislaby@kernel.org>,
"Allen Yan" <yanwei@marvell.com>,
"Miquel Raynal" <miquel.raynal@bootlin.com>,
"Gregory CLEMENT" <gregory.clement@bootlin.com>
Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] serial: mvebu-uart: correctly report configured baudrate value
Date: Tue, 28 Jun 2022 12:09:22 +0200 [thread overview]
Message-ID: <20220628100922.10717-1-pali@kernel.org> (raw)
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.
Signed-off-by: Pali Rohár <pali@kernel.org>
Fixes: 68a0db1d7da2 ("serial: mvebu-uart: add function to change baudrate")
---
drivers/tty/serial/mvebu-uart.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)
diff --git a/drivers/tty/serial/mvebu-uart.c b/drivers/tty/serial/mvebu-uart.c
index 0429c2a54290..93489fe334d0 100644
--- a/drivers/tty/serial/mvebu-uart.c
+++ b/drivers/tty/serial/mvebu-uart.c
@@ -470,14 +470,14 @@ 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;
unsigned long flags;
u32 brdv, osamp;
if (!port->uartclk)
- return -EOPNOTSUPP;
+ return 0;
/*
* The baudrate is derived from the UART clock thanks to divisors:
@@ -548,7 +548,7 @@ static int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud)
(m_divisor << 16) | (m_divisor << 24);
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,
@@ -587,15 +587,11 @@ static void mvebu_uart_set_termios(struct uart_port *port,
max_baud = port->uartclk / 80;
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) {
@@ -606,6 +602,11 @@ 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);
}
--
2.20.1
next reply other threads:[~2022-06-28 10:09 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-28 10:09 Pali Rohár [this message]
2022-06-28 10:23 ` [PATCH] serial: mvebu-uart: correctly report configured baudrate value Ilpo Järvinen
2022-06-30 8:35 ` Pali Rohár
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