Re: high priority interrupts disabled - problem found
From: Steve Rossi <hidden>
Date: 2001-12-13 15:02:34
Dan Malek wrote:
We should mask all lower priority interrupts, and the challenge is keeping the proper nesting of the masks so the nested interrupts can be "unwound" properly ...
Thanks for your followup Dan. I've got a rather straightforward "dumb" approach to fixing this problem - see the patch below. The disclaimer - I'm a hardware guy trying to do software, so there might be a much more elegant solution. The idea here is that the ppc_cached_irq_mask is maintained as is, but in addition to masking the interrupt being serviced, all lower priority interrupts are also masked. This is un-done in the unmask function, where ppc_cached_irq_mask is also used to ensure we're not un-masking interrupts that were masked prior to the call to mask_and_ack. This doesn't affect the nesting of interrupts. I might be completely missing something here, so any comments? I've tested this and it seems to work fine - and it even fixes my problem! Steve
--- ppc8xx_pic.c.orig Thu Dec 13 08:35:02 2001
+++ ppc8xx_pic.c Thu Dec 13 08:39:45 2001@@ -20,6 +20,24 @@ * but they are overkill for us. */ +static unsigned int ppc_irq_priority_mask[NR_IRQS] = { 0x0, + 0x80000000, + 0xC0000000, + 0xE0000000, + 0xF0000000, + 0xF8000000, + 0xFC000000, + 0xFE000000, + 0xFF000000, + 0xFF800000, + 0xFFC00000, + 0xFFE00000, + 0xFFF00000, + 0xFFF80000, + 0xFFFC0000, + 0xFFFE0000 + }; + static void m8xx_mask_irq(unsigned int irq_nr) { int bit, word;
@@ -41,7 +59,8 @@ ppc_cached_irq_mask[word] |= (1 << (31-bit)); ((immap_t *)IMAP_ADDR)->im_siu_conf.sc_simask = - ppc_cached_irq_mask[word]; + ppc_cached_irq_mask[word] | + (~ppc_irq_priority_mask[bit] &
ppc_cached_irq_mask[word]); } static void m8xx_mask_and_ack(unsigned int irq_nr)
@@ -53,7 +72,7 @@ ppc_cached_irq_mask[word] &= ~(1 << (31-bit)); ((immap_t *)IMAP_ADDR)->im_siu_conf.sc_simask = - ppc_cached_irq_mask[word]; + ppc_cached_irq_mask[word] &
ppc_irq_priority_mask[bit];
((immap_t *)IMAP_ADDR)->im_siu_conf.sc_sipend = 1 << (31-bit);
}
--
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Steven K. Rossi srossi@labs.mot.com
Staff Engineer
Multimedia Communications Research Laboratory
Motorola Labs
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