On Wed, 2014-06-04 at 18:03 +1000, Michael Ellerman wrote:
> On Mon, 2014-06-02 at 16:57 +1000, Michael Neuling wrote:
> > This patch enables POWER8 doorbell IPIs on powernv.
> >
> > Since doorbells can only IPI within a core, we test to see when we can use
> > doorbells and if not we fall back to XICS. This also enables hypervisor
> > doorbells to wakeup us up from nap/sleep via the LPCR PECEDH bit.
> >
> > Based on tests by Anton, the best case IPI latency between two threads
> > dropped
> > from 894ns to 512ns.
> >
> > Signed-off-by: Michael Neuling <mi...@neuling.org>
> > ---
> > arch/powerpc/kernel/cpu_setup_power.S | 2 ++
> > arch/powerpc/platforms/powernv/smp.c | 6 ++++++
> > arch/powerpc/sysdev/xics/icp-native.c | 9 ++++++++-
> > 3 files changed, 16 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/powerpc/kernel/cpu_setup_power.S
> > b/arch/powerpc/kernel/cpu_setup_power.S
> > index 1557e7c..4673353 100644
> > --- a/arch/powerpc/kernel/cpu_setup_power.S
> > +++ b/arch/powerpc/kernel/cpu_setup_power.S
> > @@ -56,6 +56,7 @@ _GLOBAL(__setup_cpu_power8)
> > li r0,0
> > mtspr SPRN_LPID,r0
> > mfspr r3,SPRN_LPCR
> > + ori r3, r3, LPCR_PECEDH
> > bl __init_LPCR
> > bl __init_HFSCR
> > bl __init_tlb_power8
> > @@ -74,6 +75,7 @@ _GLOBAL(__restore_cpu_power8)
> > li r0,0
> > mtspr SPRN_LPID,r0
> > mfspr r3,SPRN_LPCR
> > + ori r3, r3, LPCR_PECEDH
> > bl __init_LPCR
> > bl __init_HFSCR
> > bl __init_tlb_power8
> > diff --git a/arch/powerpc/platforms/powernv/smp.c
> > b/arch/powerpc/platforms/powernv/smp.c
> > index 0062a43..5fcfcf4 100644
> > --- a/arch/powerpc/platforms/powernv/smp.c
> > +++ b/arch/powerpc/platforms/powernv/smp.c
> > @@ -32,6 +32,7 @@
> > #include <asm/opal.h>
> > #include <asm/runlatch.h>
> > #include <asm/code-patching.h>
> > +#include <asm/dbell.h>
> >
> > #include "powernv.h"
> >
> > @@ -46,6 +47,11 @@ static void pnv_smp_setup_cpu(int cpu)
> > {
> > if (cpu != boot_cpuid)
> > xics_setup_cpu();
> > +
> > +#ifdef CONFIG_PPC_DOORBELL
> > + if (cpu_has_feature(CPU_FTR_DBELL))
> > + doorbell_setup_this_cpu();
> > +#endif
> > }
>
> Where does CONFIG_PPC_DOORBELL get set?
No where.
> It looks like the only place you can be getting it is from CONFIG_PPC_PSERIES.
> If you build a POWERNV only kernel it will get disabled, which I don't think
> is
> what we want.
>
> I think we should select it for POWERNV as well as PSERIES. That would mean
> it's always enabled for any build of the files you touch, so you shouldn't
> need
> the #ifdefs.
Ok, I'll add and resend.
Mikey
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