[Skiboot] [PATCH V6 3/3] occ: Add support for Version 0x90 OCC_OPAL shared memory region

[Shilpasri G Bhat]

Hi,

On 02/02/2017 10:33 AM, Benjamin Herrenschmidt wrote:
> On Thu, 2017-02-02 at 16:01 +1100, Stewart Smith wrote:
>>> Shilpasri G Bhat <shilpa.bhat at linux.vnet.ibm.com> writes:
>>> This patch enables pstate table parsing support for P9. It
>>> introduces below device tree changes.
>>> - Add a new node per chip in /ibm,opal/power-mgt called occ.
>>>>>        occ at 3ffd9f8000 {
>>>                reg = <0x3f 0xfd9f8000>;
>>>                ibm,chip-id = <0x0>;
>>>                ibm,pstate-vdds = <0x4e4e4f4f 0x4f505152 0x53545556
>>>                0x5758595a 0x5b5c5d5e 0x5f606162 0x63646565 0x66676868
>>>                0x696a6a6b 0x6c6d6d6e 0x6f6f7071 0x72727374 0x74757677
>>>                0x7778797a 0x7a7b7c7c>;
>>>                ibm,pstate-vcss = <0x4446484a 0x4c4e4f50 0x50515253
>>>                0x54555556 0x5758595a 0x5a5b5c5d 0x5d5e5e5e 0x5e5f5f5f
>>>                0x5f606060 0x61616161 0x62626263 0x63636364 0x64646465
>>>                0x65656666 0x66666767>;
>>>                ibm,pstate-core-max = <0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
>>>                phandle = <0x10000326>;
>>>        };
>>
>> Ben - any thoughts on device tree layout for ^ ?
> 
> Yup, not too sure. Looks ok but what is the core-max 0 means ?

'core-max' property holds good for WOF enabled systems where the max pstate of
the chip varies with the number of active cores.
Here core-max[0] = 0 points out the max pstate that can be attained by the chip
with 1 active core. Similarly core-max[1] is with 2 active cores and so on.

The above example is from WOF disabled system where the Pmax for N active cores
is constant which is max turbo pstate.

Thanks and Regards,
Shilpa

> 
>> I'm wondering if we need it per chip or if the information in the
>> ibm,pstate-* is mostly common, and we should just point to it rather
>> than have a copy per chip?
> 
> Maybe. Can they be different ? Vaidy ?
>>
>>> - Move VID (ibm,pstate-vdds, ibm,pstate-vcss) and max pstate for
>>>    #n active cores array (ibm,pstate-core-max) in to the new per-chip
>>>    /ibm,opal/power-mgt/occ node as these properties are unique to
>>>    chip.
>>> - WOF is supported from version 0x02. Till now we have been adding
>>>    max ultra-turbo pstate(ibm,pstate-ultra-turbo), max turbo pstate
>>>    (ibm,pstate-turbo) and max pstate-per-n-core (ibm,pstate-core-max)
>>>    only when WOF is enabled. This patch will add these properties
>>>    even when WOF is disabled. When WOF is disabled max ultra turbo pstate
>>>    equals to max turbo pstate and max pstate-per-n-core array has all
>>>    entries equal to max turbo pstate. So the above three properties
>>>    are added whenever WOF is supported to ease the reporting of these
>>>    data in host.
>>
>> Please add/enhance documentation of the applicable device tree entries
>> in doc/device-tree/ibm,opal/power-mgt.rst
>