diff mbox series

[3/8] serial: fsl_lpuart: don't restore interrupt state in ISR

Message ID 20210511200148.11934-4-michael@walle.cc
State New
Headers show
Series serial: fsl_lpuart: sysrq, loopback support and fixes | expand

Commit Message

Michael Walle May 11, 2021, 8:01 p.m. UTC 
Since commit 81e2073c175b ("genirq: Disable interrupts for force
threaded handlers") interrupt handlers that are not explicitly requested
as threaded are always called with interrupts disabled and there is no
need to save the interrupt state when taking the port lock.

This is a preparation for sysrq handling which uses
uart_unlock_and_check_sysrq();

Signed-off-by: Michael Walle <michael@walle.cc>
---
 drivers/tty/serial/fsl_lpuart.c | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

Comments

Johan Hovold May 12, 2021, 9:25 a.m. UTC | #1 
On Tue, May 11, 2021 at 10:01:43PM +0200, Michael Walle wrote:
> Since commit 81e2073c175b ("genirq: Disable interrupts for force

> threaded handlers") interrupt handlers that are not explicitly requested

> as threaded are always called with interrupts disabled and there is no

> need to save the interrupt state when taking the port lock.


Since you've copied the above words verbatim from commit 75f4e830fa9c
("serial: do not restore interrupt state in sysrq helper") I'd expect
you to use quotes or at least refer to the commit you copied the
rationale from.

> This is a preparation for sysrq handling which uses

> uart_unlock_and_check_sysrq();


Johan
Michael Walle May 12, 2021, 9:42 a.m. UTC | #2 
Am 2021-05-12 11:25, schrieb Johan Hovold:
> On Tue, May 11, 2021 at 10:01:43PM +0200, Michael Walle wrote:

>> Since commit 81e2073c175b ("genirq: Disable interrupts for force

>> threaded handlers") interrupt handlers that are not explicitly 

>> requested

>> as threaded are always called with interrupts disabled and there is no

>> need to save the interrupt state when taking the port lock.

> 

> Since you've copied the above words verbatim from commit 75f4e830fa9c

> ("serial: do not restore interrupt state in sysrq helper") I'd expect

> you to use quotes or at least refer to the commit you copied the

> rationale from.


Sure, sorry.

>> This is a preparation for sysrq handling which uses

>> uart_unlock_and_check_sysrq();


-michael
diff mbox series

Patch

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index b76ddc0d8edc..37e02d992c0b 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -824,21 +824,18 @@  static unsigned int lpuart32_tx_empty(struct uart_port *port)
 
 static void lpuart_txint(struct lpuart_port *sport)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&sport->port.lock, flags);
+	spin_lock(&sport->port.lock);
 	lpuart_transmit_buffer(sport);
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	spin_unlock(&sport->port.lock);
 }
 
 static void lpuart_rxint(struct lpuart_port *sport)
 {
 	unsigned int flg, ignored = 0, overrun = 0;
 	struct tty_port *port = &sport->port.state->port;
-	unsigned long flags;
 	unsigned char rx, sr;
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	spin_lock(&sport->port.lock);
 
 	while (!(readb(sport->port.membase + UARTSFIFO) & UARTSFIFO_RXEMPT)) {
 		flg = TTY_NORMAL;
@@ -896,28 +893,25 @@  static void lpuart_rxint(struct lpuart_port *sport)
 		writeb(UARTSFIFO_RXOF, sport->port.membase + UARTSFIFO);
 	}
 
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	spin_unlock(&sport->port.lock);
 
 	tty_flip_buffer_push(port);
 }
 
 static void lpuart32_txint(struct lpuart_port *sport)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&sport->port.lock, flags);
+	spin_lock(&sport->port.lock);
 	lpuart32_transmit_buffer(sport);
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	spin_unlock(&sport->port.lock);
 }
 
 static void lpuart32_rxint(struct lpuart_port *sport)
 {
 	unsigned int flg, ignored = 0;
 	struct tty_port *port = &sport->port.state->port;
-	unsigned long flags;
 	unsigned long rx, sr;
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	spin_lock(&sport->port.lock);
 
 	while (!(lpuart32_read(&sport->port, UARTFIFO) & UARTFIFO_RXEMPT)) {
 		flg = TTY_NORMAL;
@@ -965,7 +959,7 @@  static void lpuart32_rxint(struct lpuart_port *sport)
 	}
 
 out:
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	spin_unlock(&sport->port.lock);
 
 	tty_flip_buffer_push(port);
 }