[PATCH 3/3] Allow setup_irq call for VPE1 timer.

[PATCH 3/3] Allow setup_irq call for VPE1 timer.

[Anoop P]

From: Anoop P A <anoop.pa@gmail.com>

VSMP configuration can have seperate timer interrupts for each VPE.Need to setup IRQ for VPE1 timer.

Signed-off-by: Anoop P A <anoop.pa@gmail.com>
---
 arch/mips/kernel/cevt-r4k.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/mips/kernel/cevt-r4k.c b/arch/mips/kernel/cevt-r4k.c
index 2f4d7a9..7eaeacd 100644
--- a/arch/mips/kernel/cevt-r4k.c
+++ b/arch/mips/kernel/cevt-r4k.c
@@ -203,9 +203,10 @@ int __cpuinit r4k_clockevent_init(void)
 
 	clockevents_register_device(cd);
 
+#ifndef CONFIG_MIPS_MT_SMP
 	if (cp0_timer_irq_installed)
 		return 0;
-
+#endif
 	cp0_timer_irq_installed = 1;
 
 	setup_irq(irq, &c0_compare_irqaction);
-- 
1.7.0.4

Re: [PATCH 3/3] Allow setup_irq call for VPE1 timer.

[Ralf Baechle]

On Thu, Nov 25, 2010 at 08:37:12PM +0530, Anoop P wrote:

> From: Anoop P A <anoop.pa@gmail.com>
> 
> VSMP configuration can have seperate timer interrupts for each VPE.Need to setup IRQ for VPE1 timer.

> +#ifndef CONFIG_MIPS_MT_SMP
>  	if (cp0_timer_irq_installed)
>  		return 0;
> -
> +#endif
>  	cp0_timer_irq_installed = 1;
>  
>  	setup_irq(irq, &c0_compare_irqaction);

On the stylistic side adding an #ifdef gives me wrinkles.

With CONFIG_MIPS_MT_SMP this patch results in sharing c0_compare_irqaction
between multiple interrupts which is broken.  Struct irqaction contains
the interrupt number, all registered irqaction structs are part of a chained
list via its ->next member and also there is a per interrupt proc directory.

To fix this properly you'll have to introduce do a bit of bookkeeping - you
want to register each interrupt only once - and allocate a struct irqaction
per registered timer interrupt.

The allocation is made a little trickier by kmalloc not being available
yet by the time this code is getting invoked via time_init() so you'll
have to move it to run via the late_time_init hook like x86:

static __init void x86_late_time_init(void)
{
	... do the real work ...
}

/* ... */

void __init time_init(void)
{
        late_time_init = x86_late_time_init;
}

Which makes me wonder if there is a reason why we need to have both
time_init() and late_time_init() - can't we just move the time_init()?

  Ralf