Hello Haavard,
A few remarks:
> From: Remy Bohmer <[email protected]>
My name, at your address ;-)))
> This patch splits up the interrupt handler of the serial port
> into a interrupt top-half and a tasklet.
I see you moved the handling of the sysrq-key to the tasklet. This was
actually a very nice feature in the IRQ-top half on preempt-RT. This
helps debugging running away RT-processes.
> In this version of the patch, we try to only do things that are
> absolutely necessary in the interrupt handler, storing away the
> status register along with the received character and letting the
> tasklet handle break, sysrq, error flags, etc.
Preempt-RT now absolutely requires my (4th) IRQ_NODELAY patch, because
the spinlock now is always inside the code, and not only in
theexception path, and thus without my NO_DELAY patch we have a panic
during boot.
On preempt-RT this spinlock must be a raw-spinlock. (If this type is
known in the mainline kernel, you can apply that patch it anyway)
BTW: Attached I have added a 2nd patch that I use for Preempt-RT. (For
cleaner startup, and to get rid of useless IRQ-threads.
> This patch should apply on top of the cleanup patch I sent earlier
For the cleanup patch:
Acked-by: Remy Bohmer <[email protected]>
> today. Or at least I think so...I'll send the full series once
> everyone are happy.
So, for this patch: I am almost happy ;-)
Kind Regards,
Remy
This patch prevents starting up a useless IRQ-thread for IRQ-1,
because this IRQ is running in IRQF_NODELAY context due to the
timer interrupt.
Signed-off-by: Remy Bohmer <[email protected]>
---
drivers/serial/atmel_serial.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
Index: linux-2.6.23/drivers/serial/atmel_serial.c
===================================================================
--- linux-2.6.23.orig/drivers/serial/atmel_serial.c 2007-12-18 15:49:02.000000000 +0100
+++ linux-2.6.23/drivers/serial/atmel_serial.c 2007-12-18 15:56:37.000000000 +0100
@@ -549,6 +549,7 @@ static int atmel_startup(struct uart_por
{
struct atmel_uart_port *atmel_port = (struct atmel_uart_port *) port;
int retval;
+ unsigned long irqflags = IRQF_SHARED;
/*
* Ensure that no interrupts are enabled otherwise when
@@ -557,10 +558,17 @@ static int atmel_startup(struct uart_por
*/
UART_PUT_IDR(port, -1);
+#ifdef CONFIG_PREEMPT_RT
+ /* IRQ1 is the System IRQ, which is shared with the Timer-IRQ, and
+ thus it is running in IRQF_NODELAY context. By setting this flag
+ here also, we prevent starting up a useless IRQ-thread.*/
+ if (port->irq == 1)
+ irqflags |= IRQF_NODELAY;
+#endif
/*
* Allocate the IRQ
*/
- retval = request_irq(port->irq, atmel_interrupt, IRQF_SHARED,
+ retval = request_irq(port->irq, atmel_interrupt, irqflags,
"atmel_serial", port);
if (retval) {
printk("atmel_serial: atmel_startup - Can't get irq\n");
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