linux-kernel - [PATCH 2/2] serial: imx: Add more comments on port lock status

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Message-Id: <20240913-serial-imx-lockfix-v1-2-4d102746c89d@geanix.com>
Date: Fri, 13 Sep 2024 10:39:50 +0200
From: Esben Haabendal <esben@...nix.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Jiri Slaby <jirislaby@...nel.org>, Shawn Guo <shawnguo@...nel.org>, 
 Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, 
 John Ogness <john.ogness@...uxtronix.de>
Cc: linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org, 
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
 Esben Haabendal <esben@...nix.com>
Subject: [PATCH 2/2] serial: imx: Add more comments on port lock status

Comments regarding status of port.lock on internal functions is useful when
reviewing correct handling of registers that must be protected by this
lock.

Signed-off-by: Esben Haabendal <esben@...nix.com>
---
 drivers/tty/serial/imx.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index efa3eb3a2c57..bea4510743ef 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -370,6 +370,7 @@ static void imx_uart_soft_reset(struct imx_port *sport)
 	sport->idle_counter = 0;
 }
 
+/* called with port.lock taken and irqs off */
 static void imx_uart_disable_loopback_rs485(struct imx_port *sport)
 {
 	unsigned int uts;
@@ -470,6 +471,7 @@ static void imx_uart_stop_tx(struct uart_port *port)
 	}
 }
 
+/* called with port.lock taken and irqs off */
 static void imx_uart_stop_rx_with_loopback_ctrl(struct uart_port *port, bool loopback)
 {
 	struct imx_port *sport = to_imx_port(port);
@@ -803,6 +805,8 @@ static irqreturn_t imx_uart_txint(int irq, void *dev_id)
  * issuing soft reset to the UART (just stop/start of RX does not help). Note
  * that what we do here is sending isolated start bit about 2.4 times shorter
  * than it is to be on UART configured baud rate.
+ *
+ * Called with port.lock taken and irqs off.
  */
 static void imx_uart_check_flood(struct imx_port *sport, u32 usr2)
 {
@@ -838,6 +842,7 @@ static void imx_uart_check_flood(struct imx_port *sport, u32 usr2)
 	}
 }
 
+/* called with port.lock taken and irqs off */
 static irqreturn_t __imx_uart_rxint(int irq, void *dev_id)
 {
 	struct imx_port *sport = dev_id;
@@ -916,6 +921,7 @@ static void imx_uart_clear_rx_errors(struct imx_port *sport);
 /*
  * We have a modem side uart, so the meanings of RTS and CTS are inverted.
  */
+/* called with port.lock taken and irqs off */
 static unsigned int imx_uart_get_hwmctrl(struct imx_port *sport)
 {
 	unsigned int tmp = TIOCM_DSR;
@@ -938,6 +944,8 @@ static unsigned int imx_uart_get_hwmctrl(struct imx_port *sport)
 
 /*
  * Handle any change of modem status signal since we were last called.
+ *
+ * Called with port.lock taken and irqs off.
  */
 static void imx_uart_mctrl_check(struct imx_port *sport)
 {
@@ -1277,6 +1285,7 @@ static int imx_uart_start_rx_dma(struct imx_port *sport)
 	return 0;
 }
 
+/* called with port.lock taken and irqs off */
 static void imx_uart_clear_rx_errors(struct imx_port *sport)
 {
 	struct tty_port *port = &sport->port.state->port;
@@ -1407,6 +1416,7 @@ static int imx_uart_dma_init(struct imx_port *sport)
 	return ret;
 }
 
+/* called with port.lock taken and irqs off */
 static void imx_uart_enable_dma(struct imx_port *sport)
 {
 	u32 ucr1;

-- 
2.46.0