On Saturday 28 February 2009, Thomas Gleixner wrote: > On Sat, 28 Feb 2009, David Brownell wrote: > > Got a version that applies to mainline GIT? > > http://tglx.de/~tglx/patches.tar.bz2 Got it, thanks. > > At a quick glance it looks like these patches don't cover > > set_irq_chained_handler(), which would be trouble since > > __setup_irq() doesn't get called in those cases. > > Hmm, I did not think about chained handlers where the demux handler > needs to run in a thread as well. Usually demux handlers just have a > fast path kicking the particular real handlers. That can't work when the demux needs to access state across I2C in order to see which "real" handlers to kick. :) > > They should however handle simpler cases, like I2C devices > > that only expose one IRQ instead of needing to demux several > > dozen IRQs going to different drivers and subsystems. > > > > And, not touching lockdep, the original ugliness will still > > be needed (re-enabling IRQs in threaded handlers). > > Err ? The threaded handlers run with interrupts enabled. Hmm, I'll have a closer look. You changed handle_IRQ_event() which is where the relevant IRQF_DISABLED test kicks in. In your updated code, that pokes any quick_check_handler() and then maybe pokes a per-IRQ thread. That seems to presume a hardirq-to-taskirq handoff. But the problem case is taskirq-to-taskirq chaining, through e.g. what set_irq_chip_and_handler() provided. (Details not very amenable to brief emails, just UTSL.) Thing is, I'm not sure a per-IRQ thread can work easily with that chaining. The chained IRQs can need to be handled before the top-level IRQ gets re-enabled. That's why the twl4030-irq code uses just one taskirq thread for all incoming events. (Which of course is rarely more than one at a time, so there's little reason not to share that task between the demuxing code and the events being demuxed. Interrupts that need processing via I2C/SPI/etc are more or less by definition not frequent or performance-critical.) - Dave -- 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
