[PATCH, RESEND] microblaze: Fix level interrupt ACKing

[PATCH, RESEND] microblaze: Fix level interrupt ACKing

[steve]

Level interrupts need to be ack'd in the unmask handler, as in powerpc. 
Among other issues, this bug causes the system clock to appear to run at 
double-speed.

Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
---
diff -uprN a/arch/microblaze/kernel/intc.c b/arch/microblaze/kernel/intc.c
--- a/arch/microblaze/kernel/intc.c	2009-06-02 15:26:28.000000000 -0500
+++ b/arch/microblaze/kernel/intc.c	2009-06-02 15:27:39.000000000 -0500
@@ -41,8 +41,16 @@ unsigned int nr_irq;
 
 static void intc_enable_or_unmask(unsigned int irq)
 {
+	unsigned long mask = 1 << irq;
 	pr_debug("enable_or_unmask: %d\n", irq);
-	out_be32(INTC_BASE + SIE, 1 << irq);
+	out_be32(INTC_BASE + SIE, mask);
+
+	/* ack level irqs because they can't be acked during
+	 * ack function since the handle_level_irq function
+	 * acks the irq before calling the interrupt handler
+	 */
+	if (irq_desc[irq].status & IRQ_LEVEL)
+		out_be32(INTC_BASE + IAR, mask);
 }
 
 static void intc_disable_or_mask(unsigned int irq)

Re: [PATCH, RESEND] microblaze: Fix level interrupt ACKing

[Michal Simek]

Hi Steve,

steve@digidescorp.com wrote:
> Level interrupts need to be ack'd in the unmask handler, as in powerpc. 
> Among other issues, this bug causes the system clock to appear to run at 
> double-speed.

Can you send me any step-by-step manual how to demonstrate me this 
fault? If system clock runs at double-speed, then I should be able able 
to see that time is two times faster. Or do you mean different behavior?

Thanks,
Michal



> 
> Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
> ---
> diff -uprN a/arch/microblaze/kernel/intc.c b/arch/microblaze/kernel/intc.c
> --- a/arch/microblaze/kernel/intc.c	2009-06-02 15:26:28.000000000 -0500
> +++ b/arch/microblaze/kernel/intc.c	2009-06-02 15:27:39.000000000 -0500
> @@ -41,8 +41,16 @@ unsigned int nr_irq;
>  
>  static void intc_enable_or_unmask(unsigned int irq)
>  {
> +	unsigned long mask = 1 << irq;
>  	pr_debug("enable_or_unmask: %d\n", irq);
> -	out_be32(INTC_BASE + SIE, 1 << irq);
> +	out_be32(INTC_BASE + SIE, mask);
> +
> +	/* ack level irqs because they can't be acked during
> +	 * ack function since the handle_level_irq function
> +	 * acks the irq before calling the interrupt handler
> +	 */
> +	if (irq_desc[irq].status & IRQ_LEVEL)
> +		out_be32(INTC_BASE + IAR, mask);
>  }
>  
>  static void intc_disable_or_mask(unsigned int irq)
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/


-- 
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian

Re: [PATCH, RESEND] microblaze: Fix level interrupt ACKing

[Steven J. Magnani]

On Fri, 2009-11-20 at 12:07 +0100, Michal Simek wrote:
> Hi Steve,
> 
> steve@digidescorp.com wrote:
> > Level interrupts need to be ack'd in the unmask handler, as in powerpc. 
> > Among other issues, this bug causes the system clock to appear to run at 
> > double-speed.
> 
> Can you send me any step-by-step manual how to demonstrate me this 
> fault? If system clock runs at double-speed, then I should be able able 
> to see that time is two times faster. Or do you mean different behavior?

Unless there's a way to read jiffies_64 in userspace, the easiest way I
know of is to use the debugger. Stop the kernel soon after you boot it,
and read jiffies_64. Continue execution for some known amount of
wall-clock time, then stop the kernel again and recheck jiffies_64.
Without the patch, the number of elapsed jiffies is twice what you'd
expect based on HZ.

> 
> Thanks,
> Michal

Regards,
------------------------------------------------------------------------
 Steven J. Magnani               "I claim this network for MARS!
 www.digidescorp.com              Earthling, return my space modulator!"

 #include <standard.disclaimer>

Re: [PATCH, RESEND] microblaze: Fix level interrupt ACKing

[Michal Simek]

Steven J. Magnani wrote:
> On Fri, 2009-11-20 at 12:07 +0100, Michal Simek wrote:
>> Hi Steve,
>>
>> steve@digidescorp.com wrote:
>>> Level interrupts need to be ack'd in the unmask handler, as in powerpc. 
>>> Among other issues, this bug causes the system clock to appear to run at 
>>> double-speed.
>> Can you send me any step-by-step manual how to demonstrate me this 
>> fault? If system clock runs at double-speed, then I should be able able 
>> to see that time is two times faster. Or do you mean different behavior?
> 
> Unless there's a way to read jiffies_64 in userspace, the easiest way I
> know of is to use the debugger. Stop the kernel soon after you boot it,
> and read jiffies_64. Continue execution for some known amount of
> wall-clock time, then stop the kernel again and recheck jiffies_64.
> Without the patch, the number of elapsed jiffies is twice what you'd
> expect based on HZ.

yes, I saw that behavior. Just thinking what caused that jiffies was two 
times faster.

But anyway. I added this patch to next branch.

Thanks,
Michal

> 
>> Thanks,
>> Michal
> 
> Regards,
> ------------------------------------------------------------------------
>  Steven J. Magnani               "I claim this network for MARS!
>  www.digidescorp.com              Earthling, return my space modulator!"
> 
>  #include <standard.disclaimer>
> 
> 
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/


-- 
Michal Simek, Ing. (M.Eng)
PetaLogix - Linux Solutions for a Reconfigurable World
w: www.petalogix.com p: +61-7-30090663,+42-0-721842854 f: +61-7-30090663