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 <[email protected]> Signed-off-by: Scott Wood <[email protected]>
neviim · Apr 1, 2015 · 56302c5 · 56302c5
1 parent 88b7936
commit 56302c5
Showing 1 changed file with 0 additions and 1 deletion.
diff --git 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));
 }
 
 /*