Re: [Qemu-devel] [RFC PATCH 6/7] hw/arm/virt: Use PSCI v0.2 function IDs when kernel supports its

[Mark Rutland]

On Fri, Mar 14, 2014 at 06:53:53AM +0000, Pranavkumar Sawargaonkar wrote:
> Hi Christoffer,
> 
> On 14 March 2014 09:19, Christoffer Dall <address@hidden> wrote:
> > On Thu, Feb 27, 2014 at 12:21:07PM +0530, Pranavkumar Sawargaonkar wrote:
> >> If we have in-kernel emulation of PSCI v0.2 for KVM ARM/ARM64 then
> >> we enable PSCI v0.2 for each VCPU at the time of VCPU init hence we
> >> need to provide PSCI v0.2 function IDs via generated DTB.
> >>
> >> This patch updates generated DTB to have PSCI v0.2 function IDs when
> >> we have in-kernel emulation PSCI v0.2 for KVM ARM/ARM64.
> >>
> >> Signed-off-by: Pranavkumar Sawargaonkar <address@hidden>
> >> Signed-off-by: Anup Patel <address@hidden>
> >> ---
> >>  hw/arm/virt.c |   25 ++++++++++++++++++++-----
> >>  1 file changed, 20 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> >> index 517f2fe..a818a80 100644
> >> --- a/hw/arm/virt.c
> >> +++ b/hw/arm/virt.c
> >> @@ -187,11 +187,26 @@ static void create_fdt(VirtBoardInfo *vbi)
> >>          qemu_fdt_add_subnode(fdt, "/psci");
> >>          qemu_fdt_setprop_string(fdt, "/psci", "compatible", "arm,psci");
> >
> > was there a decision on the format of the psci 0.2 bindings?
> >
> > I seem to recall that we should add arm,psci-0.2 or something like that.
> 
> Yes there was a discussion related to that by Mark Rutland and Rob Herring :
> http://www.spinics.net/lists/arm-kernel/msg298509.html
> 
> But there is no dt binding added related to psci 0.2 in kernel (I am
> not sure about final conclusion of the dt binding to be added). If the
> dt binding gets finalized I will definitely revise this patch.
> For now I have added old binding only to test the rfc patch (may now
> be the right way to do but do not have any option also).

I believe Rob and I were happy with PSCI 0.2 IDs being implicit, though
for compatibility with existing kernels the IDs in the "arm,psci"
binding might also be listed.

The only issue was Calxeda highbank/midway systems using pre-release
PSCI 0.2 IDs for functions not in the "arm,psci" binding. For those we
could allocate a compatilbe string like "calxeda,highbank-psci-0.2" and
allow them to be implicit, or just leave them in their current
(unsupported) state.

Rob, thoughts?

Thanks,
Mark.