Messages in this thread | | | Date | Thu, 9 Feb 2012 09:40:09 +0100 | From | Lothar Waßmann <> | Subject | Re: [PATCH] genirq: Fix race condition in ONESHOT irq handler |
| |
Hi,
Thomas Gleixner writes: > On Wed, 8 Feb 2012, Lothar Waßmann wrote: > > > > The problem arises also with interrupt controllers that latch a level > > > > triggered IRQ until it is acknowledged (like the i.MX28 does). > > > > In this case the IRQ status bit will remain asserted after the > > > > soft-irq finishes and retrigger the interrupt while the interrupt line > > > > is already deasserted. > > > > > > This does not make sense. We acknowledge interrupts via mask_ack_irq() > > > right on entry of handle_level_irq(). So either the interrupt > > > > > That's right. But at that point the IRQ line is still asserted and > > since it is a level IRQ this will not actually clear the interrupt > > status bit. Normally the IRQ status bit would self-clear when the IRQ > > line is being deasserted (in this case by removing the finger from the > > touch panel). But the i.MX28 leaves the IRQ status bit set and it > > takes another write to the IRQ status register to remove the bogus IRQ > > status. > > So the question is whether the imx irq chip implementation should > write to the status register on unmask for level type irqs to avoid > spurious interrupts being generated in the first place. This is not > only an optimization for threaded interrupts, afaict this spurious > effect should happen with non threaded interrupts as well. > > Did my patch work for you ? > Sorry, I couldn't test it earlier. Yes, it works.
Lothar Waßmann -- ___________________________________________________________
Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10 Geschäftsführer: Matthias Kaussen Handelsregistereintrag: Amtsgericht Aachen, HRB 4996
www.karo-electronics.de | info@karo-electronics.de ___________________________________________________________ -- 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/
| |