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

[Rob Herring]

On Fri, Mar 14, 2014 at 5:23 AM, Mark Rutland <address@hidden> wrote:
> 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?

We need to add "arm,psci-0.2" compatible since "arm,psci" defines all
the function IDs as required and with 0.2 they are optional.

For highbank, since firmware and DTB is essentially frozen now, a
compatible change is not going to happen. It probably means just
leaving things as is.

For reference, this is what highbank/midway's binding looks like:

        psci {
                compatible      = "arm,psci";
                method          = "smc";
                cpu_suspend     = <0x84000002>;
                cpu_off         = <0x84000004>;
                cpu_on          = <0x84000006>;
                system_off      = <0x84000100>;
                system_reset    = <0x84000101>;
        };

I suppose I could just ignore the binding and make highbank reset/off
functions do custom some PSCI calls. This would mean exposing
invoke_psci_fn or creating some custom call wrapper.

Rob