From: Bogdan Purcareata Date: Tue, 24 Mar 2015 10:43:43 +0000 (+0000) Subject: powerpc/mpic: Remove WHOAMI readback after EOI X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=56302c53d3dc477b8360954fc92c1dfc4fc0ec54;p=deliverable%2Flinux.git powerpc/mpic: Remove WHOAMI readback after EOI 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 Signed-off-by: Scott Wood --- diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c index 2c817a736b77..fb19084c5860 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)); } /*