Re: [PATCH 1/3] dt: xilinx: zynqmp: Add bindings for PM firmware

[Rob Herring]

On Mon, Aug 14, 2017 at 8:47 AM, Michal Simek <michal.simek@xxxxxxxxxx> wrote:
> On 11.8.2017 15:54, Edgar E. Iglesias wrote:
>> On Fri, Aug 11, 2017 at 02:58:03PM +0200, Michal Simek wrote:
>>> Hi Rob, +Edgar,
>>>
>>> On 10.8.2017 21:10, Rob Herring wrote:
>>>> On Fri, Aug 04, 2017 at 03:45:30PM +0200, Michal Simek wrote:
>>>>> From: Soren Brinkmann <soren.brinkmann@xxxxxxxxxx>
>>>>>
>>>>> Document the DT bindings for the Zynq UltraScale+ PM Firmware.

[...]

>>>>> + - method:        The method of calling the PM-API firmware layer.
>>>>> +          Permitted values are:
>>>>> +           - "smc" : To be used in configurations without a hypervisor
>>>>> +           - "hvc" : To be used when hypervisor is present
>>>>
>>>> Do you really use both?
>>>>
>>>
>>> SMCs definitely yes.
>>>
>>> Interface was designed in that way and I don't know if people are using
>>> it or not.
>>>
>>> Not sure if Xen is blocking SMCs. I know we have discussed it but not
>>> sure if this is enabled by default or only for certain configurations.
>>> Also not sure if xen contains handler for hvc.
>>> Edgar: Do you know?
>>
>> We have patches for Xen that implement a power-management mediator.
>> That implementation handles PM calls over both SMC and HVC insns.
>> Patches are on the Xen mailing list.
>>
>> Other hypervisors may work differently.
>>
>> I think we should support both but I don't have a strong opinion on it.
>
> Rob: Are you ok with having it there?

Yes.

Rob