Messages in this thread | | | Date | Mon, 17 Dec 2012 08:37:59 -0700 | From | Jonathan Corbet <> | Subject | Re: Question about using new request_threaded_irq |
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On Mon, 17 Dec 2012 16:11:22 +0100 Marcos Lois Bermúdez <marcos.discalis@gmail.com> wrote:
> For my understand if i call for example: > > request_threaded_irq(irqmum, NULL, irq_handle, IRQF_TRIGGER_FALLING, > DEVICE_NAME, priv); > > This seem to make a old Hard IRQ handler, and inside of this handler > sleep APIs can't be used, but i see some SPI drivers that seem to > register a IRQ of this form and make API calls that can sleep in the > handler.
Not quite. The prototype for request_threaded_irq() is:
int request_threaded_irq(unsigned int irq, irq_handler_t handler, irq_handler_t thread_fn, unsigned long irqflags, const char *devname, void *dev_id)
Note the presents of *two* handlers, called "handler" and "thread_fn". The first, "handler", is called in interrupt context; it's job is usually to quiet the device and return; it cannot sleep. If it's return value is IRQ_WAKE_THREAD, the thread_fn() will be called in process context; it *can* sleep. In the example you cite, there is no immediate handler, only the thread_fn(); the call to a blocking function from within the thread_fn() is correct.
Hope that helps,
jon
Jonathan Corbet / LWN.net / corbet@lwn.net -- 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/
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