Messages in this thread | | | Subject | Re: [RFC] PPC: MPIC: necessary readback after EOI? | From | Benjamin Herrenschmidt <> | Date | Wed, 07 Jan 2015 15:44:36 +0100 |
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On Mon, 2015-01-05 at 12:10 -0600, Scott Wood wrote: > It would have been nice if a code comment explained why it was doing the > readback... I don't see any particular need to wait for EOI completion > here (unlike when masking).
The EOI is what causes the MPIC to drop it's EE output to the CPU, if the EOI is processed too slowly & asynchronously (posted write + 33Mhz MPIC) we observe cases of spurrious interrupts. We had some macs basically getting a spurrious irq for every MPIC interrupts...
Cheers, Ben.
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