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SubjectRe: [PATCH RFT] irqchip: sun4i: Remove wrong irq_ack callback implementation
Hi Geert,

On Fri, Jul 19, 2013 at 11:29:30AM +0200, Geert Uytterhoeven wrote:
> On Thu, Jul 11, 2013 at 6:13 PM, Maxime Ripard
> <> wrote:
> > On Sat, Jul 06, 2013 at 10:35:29PM +0800, Axel Lin wrote:
> >> According to the datasheet[1], the Interrupt IRQ Pending Registers are
> >> read-only. The implementation of sun4i_irq_ack() looks wrong because it writes
> >> to these read-only registers.
> >
> > Right, but the datasheet also says that these registers are "clear"
> > register, which might indicate that it's actually R/W.
> I guess it means that the flags are cleared automatically on read?
> That's not so uncommon for interrupt pending registers.

My understanding in this case is that the pending register is just a
"copy" of the pending bits in the related hardware IP, so that clearing
it in the interrupt controller won't do much, since it will be re-set
just after the clear, while if you do clear the interrupt bit in the IP,
it will clear it automatically in the interrupt controller.


Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
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