Messages in this thread | | | Date | Sun, 19 Jul 2015 00:18:37 +0200 | From | Alexandre Belloni <> | Subject | Re: [PATCH 3/3] clocksource: atmel-pit: Remove irq handler when clock event is unused |
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On 18/07/2015 at 10:20:53 +0200, Thomas Gleixner wrote : > On Fri, 17 Jul 2015, Alexandre Belloni wrote: > > /* > > + * IRQ handler for the timer. > > + */ > > +static irqreturn_t at91sam926x_pit_interrupt(int irq, void *dev_id) > > +{ > > + struct pit_data *data = dev_id; > > + > > + /* > > + * irqs should be disabled here, but as the irq is shared they are only > > + * guaranteed to be off if the timer irq is registered first. > > That's wrong. We run all handlers with interrupts disabled for about 5 > years now. > > > + */ > > + WARN_ON_ONCE(!irqs_disabled()); >
Yeah, I was skeptical when I read that...
> > > + /* The PIT interrupt may be disabled, and is shared */ > > + if (clockevent_state_periodic(&data->clkevt) && > > + (pit_read(data->base, AT91_PIT_SR) & AT91_PIT_PITS)) { > > + unsigned nr_ticks; > > + > > + /* Get number of ticks performed before irq, and ack it */ > > + nr_ticks = PIT_PICNT(pit_read(data->base, AT91_PIT_PIVR)); > > + do { > > + data->cnt += data->cycle; > > + data->clkevt.event_handler(&data->clkevt); > > + nr_ticks--; > > + } while (nr_ticks); > > I don't think you need this loop. You have a proper clocksource > registered so the timekeeping code will handle the lost ticks nicely. >
... for both comments, this is just code I'm moving from one place to another. I'll have a look a clean that up in a preliminary patch. Thanks!
-- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com
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