On Mon, 27 Jan 2014, Russell King - ARM Linux wrote: > On Mon, Jan 27, 2014 at 01:08:16AM -0500, Nicolas Pitre wrote: > > ARM and ARM64 are the only two architectures implementing > > arch_cpu_idle_prepare() simply to call local_fiq_enable(). > > > > We have secondary_start_kernel() already calling local_fiq_enable() and > > this is done a second time in arch_cpu_idle_prepare() in that case. And > > enabling FIQs has nothing to do with idling the CPU to start with. > > > > So let's introduce init_fiq_boot_cpu() to take care of FIQs on the boot > > CPU and remove arch_cpu_idle_prepare(). This is now done a bit earlier > > at late_initcall time but this shouldn't make a difference in practice > > i.e. when FIQs are actually used. > > > > Signed-off-by: Nicolas Pitre <n...@linaro.org> > > --- > > arch/arm/kernel/process.c | 5 ----- > > arch/arm/kernel/setup.c | 7 +++++++ > > 2 files changed, 7 insertions(+), 5 deletions(-) > > > > diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c > > index 92f7b15dd2..725b8c95e0 100644 > > --- a/arch/arm/kernel/process.c > > +++ b/arch/arm/kernel/process.c > > @@ -142,11 +142,6 @@ static void default_idle(void) > > local_irq_enable(); > > } > > > > -void arch_cpu_idle_prepare(void) > > -{ > > - local_fiq_enable(); > > -} > > - > > void arch_cpu_idle_enter(void) > > { > > ledtrig_cpu(CPU_LED_IDLE_START); > > diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c > > index 987a7f5bce..d027b1a6fe 100644 > > --- a/arch/arm/kernel/setup.c > > +++ b/arch/arm/kernel/setup.c > > @@ -789,6 +789,13 @@ static int __init init_machine_late(void) > > } > > late_initcall(init_machine_late); > > > > +static int __init init_fiq_boot_cpu(void) > > +{ > > + local_fiq_enable(); > > + return 0; > > +} > > +late_initcall(init_fiq_boot_cpu); > > arch_cpu_idle_prepare() gets called from the swapper thread, and changes > the swapper thread's CPSR. init_fiq_boot_cpu() gets called from PID1, the > init thread, and changes the init thread's CPSR, which will already have > FIQs enabled by way of how kernel threads are created. > > Hence, the above code fragment has no effect what so ever, and those > platforms using FIQs will not have FIQs delivered if they're idle > (because the swapper will have FIQs masked at the CPU.)
You're right. What about moving local_fiq_enable() to trap_init() then? Nicolas _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev