All of lore.kernel.org
 help / color / mirror / Atom feed
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


             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 ` Ilpo Järvinen
2022-06-30  8:35   ` Pali Rohár

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220628100922.10717-1-pali@kernel.org \
    --to=pali@kernel.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=gregory.clement@bootlin.com \
    --cc=ilpo.jarvinen@linux.intel.com \
    --cc=jirislaby@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-serial@vger.kernel.org \
    --cc=miquel.raynal@bootlin.com \
    --cc=yanwei@marvell.com \
    --subject='Re: [PATCH] serial: mvebu-uart: correctly report configured baudrate value' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.