On Fri, 27 Feb 2009 20:46:50 -0800 David Brownell <david-b@xxxxxxxxxxx> wrote: > drivers/mfd/twl4030-irq.c > > Where you'll observe twl_init_irq() at line 688 setting > up the thread and the Primary IRQ Handler (PIH) dispatch. > That's pretty much bog-standard chained IRQ setup code, > except that it chains through a thread. OK, that's clever. I never knew that anyone was doing that. afaict MFD is the only such place... Yes, it's regrettable that it's a private-to-mfd implementation. I expect a lot of i2c clients (at least) would like this. > When an IRQ comes in, handle_twl4030_pih() acks and masks > that top level IRQ. Then it wakes twl4030_irq_thread(), > which issues I2C operations to read the IRQ status from > the chip ... first PIH to find out which SIH modules are > raising an IRQ, then SIH to dispatch that status. Then > handle_irq() from that thread to invoke the handler in > that thread context; it will issue more I2C ops. yup. > And the lockdep thing kicks in through handle_irq(), > where the IRQ handler wrongly gets invoked with the > IRQs disabled -- iff lockdep is enabled. Otherwise, > that IRQ thread is just like any other thread. OK. Perhaps it would be somewhat less dirty to do something like --- a/kernel/irq/manage.c~a +++ a/kernel/irq/manage.c @@ -689,7 +689,8 @@ int request_irq(unsigned int irq, irq_ha /* * Lockdep wants atomic interrupt handlers: */ - irqflags |= IRQF_DISABLED; + if (!(irqflags & IRQF_NO_LOCKDEP_HACK)) + irqflags |= IRQF_DISABLED; #endif /* * Sanity-check: shared interrupts must pass in a real dev-ID, _ -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
