linux-kernel - [PATCH tty-next v1 4/4] serial: 8250: Explain the role of @read_status

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Message-Id: <20241216171244.12783-5-john.ogness@linutronix.de>
Date: Mon, 16 Dec 2024 18:18:44 +0106
From: John Ogness <john.ogness@...utronix.de>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Jiri Slaby <jirislaby@...nel.org>,
	Esben Haabendal <esben@...nix.com>,
	linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Kevin Hilman <khilman@...libre.com>,
	Markus Schneider-Pargmann <msp@...libre.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Udit Kumar <u-kumar1@...com>,
	Griffin Kroah-Hartman <griffin@...ah.com>,
	Arnd Bergmann <arnd@...db.de>,
	Rengarajan S <rengarajan.s@...rochip.com>,
	Bart Van Assche <bvanassche@....org>,
	Niklas Schnelle <schnelle@...ux.ibm.com>,
	Serge Semin <fancer.lancer@...il.com>,
	Lino Sanfilippo <l.sanfilippo@...bus.com>,
	Peter Collingbourne <pcc@...gle.com>
Subject: [PATCH tty-next v1 4/4] serial: 8250: Explain the role of @read_status_mask

The role of @read_status_mask has changed over time and seems
to still cause confusion. This can be expected since there is
zero documentation about this driver-specific variable.

Add comments to the initialization of @read_status_mask to
clarify its role.

Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
 drivers/tty/serial/8250/8250_omap.c | 6 ++++++
 drivers/tty/serial/8250/8250_port.c | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 10144fcc0363..42b4aa56b902 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -412,6 +412,12 @@ static void omap_8250_set_termios(struct uart_port *port,
 	 */
 	uart_update_timeout(port, termios->c_cflag, baud);
 
+	/*
+	 * Specify which conditions may be considered for error
+	 * handling and the ignoring of characters. The actual
+	 * ignoring of characters only occurs if the bit is set
+	 * in @ignore_status_mask as well.
+	 */
 	up->port.read_status_mask = UART_LSR_OE | UART_LSR_DR;
 	if (termios->c_iflag & INPCK)
 		up->port.read_status_mask |= UART_LSR_FE | UART_LSR_PE;
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 3b9dc2bb06eb..1a65d3e5f3c0 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2785,6 +2785,12 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
 	 */
 	uart_update_timeout(port, termios->c_cflag, baud);
 
+	/*
+	 * Specify which conditions may be considered for error
+	 * handling and the ignoring of characters. The actual
+	 * ignoring of characters only occurs if the bit is set
+	 * in @ignore_status_mask as well.
+	 */
 	port->read_status_mask = UART_LSR_OE | UART_LSR_DR;
 	if (termios->c_iflag & INPCK)
 		port->read_status_mask |= UART_LSR_FE | UART_LSR_PE;
-- 
2.39.5