Re: Clocks used by another OS/CPU (was: Re: [RFC PATCH] clk: renesas: cpg-mssr: Add interface for critical core clocks)

[Sudeep Holla <sudeep.holla@arm.com>]

On 04/07/17 08:31, Peter De Schrijver wrote:
> On Mon, Jul 03, 2017 at 10:17:22AM +0100, Sudeep Holla wrote:
>>
>>
>> On 01/07/17 19:14, Uwe Kleine-König wrote:
>>> Hello,
>>>
>>> On Sat, Jul 01, 2017 at 07:02:48AM +0200, Dirk Behme wrote:
>>
>> [...]
>>
>>>>
>>>>
>>>> The other problem is security related. If, at all, you have to do it the
>>>> other way around, then:
>>>>
>>>> Make Linux a consumer of the other CPU's (trusted/trustzone/whatever
>>>> secured) OS clock driver.
>>
>> Yes, that's better and is getting common on newer platforms. They have
>> separate M-class(or even low A-class e.g. A5/A7) processors to handle
>> all the system management.
>>
>> The new ARM SCMI specification[0][1] is designed to standardize the
>> interface. It covers the clocks in clock protocol.
>>
> 
> Yes, however this doesn't exist on older SoCs which still have multiple CPU's
> 

Agreed. But if someone is fixing/adding support in Linux as well as in
the other OS running on those cores, why not consider this interface
instead of trying to generalize something which will invariably SoC
specific.
-- 
Regards,
Sudeep