From: Andrew Parlane <andrewp@carallon.com>
To: Nick Garnett <nickg@calivar.com>, ecos-discuss@ecos.sourceware.org
Subject: Re: [ECOS] Spurious interrupt on ARM.
Date: Fri, 01 Nov 2013 17:20:00 -0000 [thread overview]
Message-ID: <5273E2EE.3010908@carallon.com> (raw)
In-Reply-To: <5273DFAE.1080000@calivar.com>
Sorry, I should have been a bit more clear.
First we skip the ISR by jumping to the spurious_IRQ label, and then we
switch stacks if necessary, then we have (line numbers may vary):
941 // The return value from the handler (in r0) will indicate
whether a
942 // DSR is to be posted. Pass this together with a pointer to the
943 // interrupt object we have just used to the interrupt tidy
up routine.
944
945 // don't run this for spurious interrupts!
946 cmp v1,#CYGNUM_HAL_INTERRUPT_NONE
947 beq 17f
948 ldr r1,.hal_interrupt_objects
949 ldr r1,[r1,v1,lsl #2]
950 mov r2,v6 // register frame
951
952 THUMB_MODE(r3,10)
953
954 bl interrupt_end // post any bottom layer handler
955 // threads and call scheduler
956 ARM_MODE(r1,10)
957 17:
So it compares the result of hal_IRQ_handler (stored in v1) with
CYGNUM_HAL_INTERRUPT_NONE, and jumps forwards to label 17: which is
after interrupt_end. if it was a spurious IRQ.
Andrew
On 01/11/2013 17:06, Nick Garnett wrote:
>
> On 31/10/13 17:15, Andrew Parlane wrote:
>> Looking at hal/arm/arch/current/src/vectors.S in IRQ:
>>
>> We increment the scheduler lock and decrement it again in interrupt_end.
>>
>> In the case of there being a spurious interrupt, we don't call
>> interrupt_end, and so the scheduler never gets decremented.
>>
>> Am I missing something here?
> interrupt_end() does get called. A spurious interrupt only causes the
> code to skip calling an ISR by jumping to the spurious_IRQ label. From
> there it follows the same code path and will call interrupt_end() as normal.
>
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next prev parent reply other threads:[~2013-11-01 17:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-31 17:15 Andrew Parlane
2013-11-01 17:06 ` Nick Garnett
2013-11-01 17:20 ` Andrew Parlane [this message]
2013-11-01 17:42 ` Nick Garnett
2013-11-01 17:46 ` Andrew Parlane
2013-11-01 17:50 ` Nick Garnett
2013-11-01 17:54 ` Andrew Parlane
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