Messages in this thread | | | From | Alexander Stein <> | Subject | Re: [PATCH v2 2/2] ARM: at91: pm: switch to the PIE infrastructure | Date | Wed, 29 Jun 2016 10:30:55 +0200 |
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On Wednesday 29 June 2016 09:57:14, Alexandre Belloni wrote: > On 29/06/2016 at 08:12:21 +0200, Alexander Stein wrote : > > > +#if defined(CONFIG_CPU_V7) > > > + dsb(); > > > + wfi(); > > > +#else > > > + asm volatile ("mcr p15, 0, %0, c7, c0, 4" \ > > > + : : "r" (0) : "memory"); > > > +#endif > > > > Why not defining wfi() for __LINUX_ARM_ARCH__ < 7 as it is done for dsb() > > and friends in arch/arm/include/asm/barrier.h? So you can get rid of that > > #if completly. > > Well, Russell said it was not useful because "there's no architected WFI > instruction which doesn't have CPU specific issues (hence why we have > cpu_do_idle() to abstract that)"
Wouldn't you suffer from this here as well? Anyway, the inline assembly above is what is actually wfi but using CP15. I checked several proc-*.S in do_idle and they all have > "mcr p15, 0, r0, c7, c0, 4 @ Wait for interrupt" at some point. so this inline assembly could actually be implemented on wfi() macro.
Best regards, Alexander
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