Re: [PATCH] Arm: GICv3: Don't access GIC_ICDIPR for interrupts 0..31

[Leif Lindholm <leif.lindholm@linaro.org>]

On Fri, May 19, 2017 at 05:37:02AM +0300, Sergei Temerkhanov wrote:
> On Thu, May 18, 2017 at 7:08 PM, Ard Biesheuvel
> <ard.biesheuvel@linaro.org> wrote:
> > On 16 May 2017 at 03:56, Sergey Temerkhanov <s.temerkhanov@gmail.com> wrote:
> >> These registers are reserved for PPIs and unimplemented on
> >> some architectures
> >>
> >
> >
> > What do you mean by 'architectures'?
> 
> GIC core implementations.
> 
> > Could you elaborate on which SoC
> > needs this?
> At least Cavium ThunderX/OcteonTX need it.
> 
> The GICv3 spec says this on the subject:
> 
> 8.9.12 GICD_IPRIORITYR, Interrupt Priority Registers, n = 0 - 254
> 
> "These registers are always used when affinity routing is not enabled.
> When affinity routing is enabled for the Security state of an
> interrupt: • GICR_IPRIORITYR is used instead of GICD_IPRIORITYR where
> n = 0 to 7 (that is, for SGIs and PPIs). • GICD_IPRIORITYR is RAZ/WI
> where n = 0 to 7."

Since they are RAZ/WI, why is this change needed?

/
    Leif

> >
> >> Signed-off-by: Sergey Temerkhanov <s.temerkhanov@gmail.com>
> >> ---
> >>  ArmPkg/Drivers/ArmGic/GicV3/ArmGicV3Dxe.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/ArmPkg/Drivers/ArmGic/GicV3/ArmGicV3Dxe.c b/ArmPkg/Drivers/ArmGic/GicV3/ArmGicV3Dxe.c
> >> index 8af97a9..dc6b896 100644
> >> --- a/ArmPkg/Drivers/ArmGic/GicV3/ArmGicV3Dxe.c
> >> +++ b/ArmPkg/Drivers/ArmGic/GicV3/ArmGicV3Dxe.c
> >> @@ -257,7 +257,7 @@ GicV3DxeInitialize (
> >>      MmioOr32 (mGicDistributorBase + ARM_GIC_ICDDCR, ARM_GIC_ICDDCR_ARE);
> >>    }
> >>
> >> -  for (Index = 0; Index < mGicNumInterrupts; Index++) {
> >> +  for (Index = 32; Index < mGicNumInterrupts; Index++) {
> >>      GicV3DisableInterruptSource (&gHardwareInterruptV3Protocol, Index);
> >>
> >>      // Set Priority
> >> --
> >> 2.7.4
> >>
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