[Skiboot] [PATCH v2 4/5] occ: Export per-chip Vid in device tree

[Shilpasri G Bhat]

Hi,

On 06/09/2016 12:44 PM, Stewart Smith wrote:
> Shilpasri G Bhat <shilpa.bhat at linux.vnet.ibm.com> writes:
>> This patch moves ibm,pstate-vcss and ibm,pstate-vdds property
>> from /ibm,opal/power-mgt to /ibm,opal/power-mgt/occ@<addr> node.
>> Should these properties be retained in 'power-mgt' node to avoid
>> breakage?
> 
> Does anything use them? Has anything (EVER) used them?

This data is mainly consumed by hardware characterization team for WOF. They
wanted a per-chip VID in P8+ for WOF characterization.

[Currently, the kernel cpufreq driver does not read these Voltage-ID properties.
Characterization team is the one user I am aware of.]

> 
> If so, we could always keep them on P8 and just have them move in P9 (if
> this is the case, we should start some documentation on changes done for
> p9 so that in the future when we remove p7/p8 support, we know what we
> can remove from skiboot and kernel)
> 

Okay. So in P8 we will have DT as below:

/ibm,opal/power-mgt {
	...
	ibm,pstate-vcss:
	ibm,pstate-vdds:

	occ@<addr> {
		ibm,pstate-vcss:
		ibm,pstate-vdds:
		...
	}
	...
}


And in P9 we can get rid of /ibm,opal/power-mgt/ibm,pstate-v{css/dds}.

Thanks and Regards,
Shilpa