Messages in this thread | | | Date | Wed, 13 May 2015 15:23:01 +0300 | From | Purcareata Bogdan <> | Subject | Re: [PATCH] powerpc/mpic: Remove WHOAMI readback after EOI |
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On 24.03.2015 12:43, Bogdan Purcareata wrote: > After previous discussions regarding the subject [1][2], there's no clear > explanation or reason why the call was needed in the first place. The sensible > argument is some sort of synchronization between the CPU and the MPIC, which > hasn't been pointed out precisely and is no longer required (at least on BookE > platforms). > > The benefit of this change is saving a MMIO trap per interrupt when running in a > KVM guest. > > [1] https://patchwork.ozlabs.org/patch/429098/ > [2] https://patchwork.ozlabs.org/patch/433557/ > > Signed-off-by: Bogdan Purcareata <bogdan.purcareata@freescale.com> > --- > arch/powerpc/sysdev/mpic.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c > index bbfbbf2..045e72a9 100644 > --- a/arch/powerpc/sysdev/mpic.c > +++ b/arch/powerpc/sysdev/mpic.c > @@ -655,7 +655,6 @@ static inline struct mpic * mpic_from_irq_data(struct irq_data *d) > static inline void mpic_eoi(struct mpic *mpic) > { > mpic_cpu_write(MPIC_INFO(CPU_EOI), 0); > - (void)mpic_cpu_read(MPIC_INFO(CPU_WHOAMI)); > } > > /* >
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