[RT,1/1] tty/serial/sifive: Make the locking RT aware

[RT,1/1] tty/serial/sifive: Make the locking RT aware

[ende.tan]

From: Tan En De <ende.tan@starfivetech.com>

The lock is a sleeping lock and local_irq_save() is not the optimsation
we are looking for. Redo it to make it work on -RT and non-RT.

Signed-off-by: Tan En De <ende.tan@starfivetech.com>
Signed-off-by: Tan Ley Foon <leyfoon.tan@starfivetech.com>
---
 drivers/tty/serial/sifive.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index b296e57a9dee..074c9f392634 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -791,13 +791,10 @@ static void sifive_serial_console_write(struct console *co, const char *s,
 	if (!ssp)
 		return;
 
-	local_irq_save(flags);
-	if (ssp->port.sysrq)
-		locked = 0;
-	else if (oops_in_progress)
-		locked = uart_port_trylock(&ssp->port);
+	if (ssp->port.sysrq || oops_in_progress)
+		locked = uart_port_trylock_irqsave(&ssp->port, &flags);
 	else
-		uart_port_lock(&ssp->port);
+		uart_port_lock_irqsave(&ssp->port, &flags);
 
 	ier = __ssp_readl(ssp, SIFIVE_SERIAL_IE_OFFS);
 	__ssp_writel(0, SIFIVE_SERIAL_IE_OFFS, ssp);
@@ -807,8 +804,7 @@ static void sifive_serial_console_write(struct console *co, const char *s,
 	__ssp_writel(ier, SIFIVE_SERIAL_IE_OFFS, ssp);
 
 	if (locked)
-		uart_port_unlock(&ssp->port);
-	local_irq_restore(flags);
+		uart_port_unlock_irqrestore(&ssp->port, flags);
 }
 
 static int sifive_serial_console_setup(struct console *co, char *options)
-- 
2.34.1

Re: [RT,1/1] tty/serial/sifive: Make the locking RT aware

[Sebastian Andrzej Siewior]

On 2024-12-03 17:40:09 [+0800], ende.tan@starfivetech.com wrote:
> From: Tan En De <ende.tan@starfivetech.com>
> 
> The lock is a sleeping lock and local_irq_save() is not the optimsation
> we are looking for. Redo it to make it work on -RT and non-RT.

You need to state which kernel this needs to be applied to.
The change you looking for is
	32c694ec3efc2 ("serial: sifive: Use uart_prepare_sysrq_char() to handle sysrq.")

> Signed-off-by: Tan En De <ende.tan@starfivetech.com>
> Signed-off-by: Tan Ley Foon <leyfoon.tan@starfivetech.com>

Sebastian

RE: [RT,1/1] tty/serial/sifive: Make the locking RT aware

[EnDe Tan]

> -----Original Message-----
> You need to state which kernel this needs to be applied to.
> The change you looking for is
> 	32c694ec3efc2 ("serial: sifive: Use uart_prepare_sysrq_char() to
> handle sysrq.")

Thanks for pointing this out, I overlooked the commit in the mainline kernel.
BTW, the commit is not in v6.6.63-rt46-rebase. 

Re: RE: [RT,1/1] tty/serial/sifive: Make the locking RT aware

[Sebastian Andrzej Siewior]

On 2024-12-04 15:24:38 [+0000], EnDe Tan wrote:
> > -----Original Message-----
> > You need to state which kernel this needs to be applied to.
> > The change you looking for is
> > 	32c694ec3efc2 ("serial: sifive: Use uart_prepare_sysrq_char() to
> > handle sysrq.")
> 
> Thanks for pointing this out, I overlooked the commit in the mainline kernel.
> BTW, the commit is not in v6.6.63-rt46-rebase. 

Indeed. Clark, could you please backport
	32c694ec3efc2 serial: sifive: Use uart_prepare_sysrq_char() to handle sysrq.

for v6.6-RT?

Sebastian

Re: RE: [RT,1/1] tty/serial/sifive: Make the locking RT aware

[Clark Williams]

yes, I'll put it in my pending RC

On Thu, Dec 5, 2024 at 8:06 AM Sebastian Andrzej Siewior
<bigeasy@linutronix.de> wrote:
>
> On 2024-12-04 15:24:38 [+0000], EnDe Tan wrote:
> > > -----Original Message-----
> > > You need to state which kernel this needs to be applied to.
> > > The change you looking for is
> > >     32c694ec3efc2 ("serial: sifive: Use uart_prepare_sysrq_char() to
> > > handle sysrq.")
> >
> > Thanks for pointing this out, I overlooked the commit in the mainline kernel.
> > BTW, the commit is not in v6.6.63-rt46-rebase.
>
> Indeed. Clark, could you please backport
>         32c694ec3efc2 serial: sifive: Use uart_prepare_sysrq_char() to handle sysrq.
>
> for v6.6-RT?
>
> Sebastian
>