On Wed, 2015-12-16 at 06:37AM -0800, Peter Hurley wrote: > On 12/16/2015 01:03 AM, Sören Brinkmann wrote: > > On Tue, 2015-12-15 at 03:26PM -0800, Peter Hurley wrote: > >> On 12/15/2015 07:41 AM, Sören Brinkmann wrote: > >>> On Thu, 2015-12-10 at 01:41PM -0800, Peter Hurley wrote: > >>>> On 12/05/2015 08:39 PM, Soren Brinkmann wrote: > >>>>> Request_irq() should be _after_ h/w programming, otherwise an > >>>>> interrupt could be triggered and in-progress before the h/w has been > >>>>> setup. > >>>> > >>>> Slight misunderstanding. My fault; I should have been more explicit. > >>>> > >>>> 1. Any setup necessary for the isr not to be confused and misdirect spurious > >>>> interrupts (or hang) should be before installing the isr with request_irq() > >>>> None of this code should trigger an interrupt. > >>>> 2. Clear pending interrupts > >>>> 3. Install the isr with request_irq() > >>>> 4. Enable interrupts > >>> > >>> Isn't that what the startup function is doing now - more or less. I > >>> think 3 and 4 are swapped to release the lock and then do the > >>> request_irq, but I believe that should be OK. > >>> The startup function configures the HW. Clears the ISR. Enables the > >>> intended IRQs and then does the request_irq call. > >> > >> If the driver enables interrupts before installing the isr with request_irq() > >> and an interrupt occurs there will the no handler to catch it and EOI the > >> device. > > > > Really? Shouldn't the IRQ be masked in the interrupt controller until > > everything is in place? > > Sorry, I'm used to shared interrupts, where that isn't the case. Ahh, I didn't have to deal with such cases yet. Makes sense though. Thanks, Sören -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
