Re: [PATCH] powernv: powercap: Add hard minimum powercap

[Shilpasri G Bhat]

Hi,

On 02/28/2019 10:14 AM, Daniel Axtens wrote:
> Shilpasri G Bhat <shilpa.bhat@xxxxxxxxxxxxxxxxxx> writes:
> 
>> In POWER9, OCC(On-Chip-Controller) provides for hard and soft system
>> powercapping range. The hard powercap range is guaranteed while soft
>> powercap may or may not be asserted due to various power-thermal
>> reasons based on system configuration and workloads. This patch adds
>> a sysfs file to export the hard minimum powercap limit to allow the
>> user to set the appropriate powercap value that can be managed by the
>> system.
> 
> Maybe it's common terminology and I'm just not aware of it, but what do
> you mean by "asserted"? It doesn't appear elsewhere in the documentation
> you're patching, and it's not a use of assert that I'm familiar with...
> 
> Regards,
> Daniel
> 

I meant to say powercap will not be assured in the soft powercap range, i.e,
system may or may not be throttled of CPU frequency to remain within the powercap.

I can reword the document and commit message.

Thanks and Regards,
Shilpa

>>
>> Signed-off-by: Shilpasri G Bhat <shilpa.bhat@xxxxxxxxxxxxxxxxxx>
>> ---
>>  .../ABI/testing/sysfs-firmware-opal-powercap       | 10 ++++
>>  arch/powerpc/platforms/powernv/opal-powercap.c     | 66 +++++++++-------------
>>  2 files changed, 37 insertions(+), 39 deletions(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-firmware-opal-powercap b/Documentation/ABI/testing/sysfs-firmware-opal-powercap
>> index c9b66ec..65db4c1 100644
>> --- a/Documentation/ABI/testing/sysfs-firmware-opal-powercap
>> +++ b/Documentation/ABI/testing/sysfs-firmware-opal-powercap
>> @@ -29,3 +29,13 @@ Description:	System powercap directory and attributes applicable for
>>  		  creates a request for setting a new-powercap. The
>>  		  powercap requested must be between powercap-min
>>  		  and powercap-max.
>> +
>> +What:		/sys/firmware/opal/powercap/system-powercap/powercap-hard-min
>> +Date:		Feb 2019
>> +Contact:	Linux for PowerPC mailing list <linuxppc-dev@xxxxxxxxxx>
>> +Description:	Hard minimum powercap
>> +
>> +		This file provides the hard minimum powercap limit in
>> +		Watts. The powercap value above hard minimum is always
>> +		guaranteed to be asserted and the powercap value below
>> +		the hard minimum limit may or may not be guaranteed.
>> diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c
>> index d90ee4f..38408e7 100644
>> --- a/arch/powerpc/platforms/powernv/opal-powercap.c
>> +++ b/arch/powerpc/platforms/powernv/opal-powercap.c
>> @@ -139,10 +139,24 @@ static void powercap_add_attr(int handle, const char *name,
>>  	attr->handle = handle;
>>  	sysfs_attr_init(&attr->attr.attr);
>>  	attr->attr.attr.name = name;
>> -	attr->attr.attr.mode = 0444;
>> +
>> +	if (!strncmp(name, "powercap-current", strlen(name))) {
>> +		attr->attr.attr.mode = 0664;
>> +		attr->attr.store = powercap_store;
>> +	} else {
>> +		attr->attr.attr.mode = 0444;
>> +	}
>> +
>>  	attr->attr.show = powercap_show;
>>  }
>>  
>> +static const char * const powercap_strs[] = {
>> +	"powercap-max",
>> +	"powercap-min",
>> +	"powercap-current",
>> +	"powercap-hard-min",
>> +};
>> +
>>  void __init opal_powercap_init(void)
>>  {
>>  	struct device_node *powercap, *node;
>> @@ -167,60 +181,34 @@ void __init opal_powercap_init(void)
>>  
>>  	i = 0;
>>  	for_each_child_of_node(powercap, node) {
>> -		u32 cur, min, max;
>> -		int j = 0;
>> -		bool has_cur = false, has_min = false, has_max = false;
>> +		u32 id;
>> +		int j, count = 0;
>>  
>> -		if (!of_property_read_u32(node, "powercap-min", &min)) {
>> -			j++;
>> -			has_min = true;
>> -		}
>> -
>> -		if (!of_property_read_u32(node, "powercap-max", &max)) {
>> -			j++;
>> -			has_max = true;
>> -		}
>> +		for (j = 0; j < ARRAY_SIZE(powercap_strs); j++)
>> +			if (!of_property_read_u32(node, powercap_strs[j], &id))
>> +				count++;
>>  
>> -		if (!of_property_read_u32(node, "powercap-current", &cur)) {
>> -			j++;
>> -			has_cur = true;
>> -		}
>> -
>> -		pcaps[i].pattrs = kcalloc(j, sizeof(struct powercap_attr),
>> +		pcaps[i].pattrs = kcalloc(count, sizeof(struct powercap_attr),
>>  					  GFP_KERNEL);
>>  		if (!pcaps[i].pattrs)
>>  			goto out_pcaps_pattrs;
>>  
>> -		pcaps[i].pg.attrs = kcalloc(j + 1, sizeof(struct attribute *),
>> +		pcaps[i].pg.attrs = kcalloc(count + 1,
>> +					    sizeof(struct attribute *),
>>  					    GFP_KERNEL);
>>  		if (!pcaps[i].pg.attrs) {
>>  			kfree(pcaps[i].pattrs);
>>  			goto out_pcaps_pattrs;
>>  		}
>>  
>> -		j = 0;
>>  		pcaps[i].pg.name = kasprintf(GFP_KERNEL, "%pOFn", node);
>> -		if (has_min) {
>> -			powercap_add_attr(min, "powercap-min",
>> -					  &pcaps[i].pattrs[j]);
>> -			pcaps[i].pg.attrs[j] = &pcaps[i].pattrs[j].attr.attr;
>> -			j++;
>> -		}
>> -
>> -		if (has_max) {
>> -			powercap_add_attr(max, "powercap-max",
>> -					  &pcaps[i].pattrs[j]);
>> -			pcaps[i].pg.attrs[j] = &pcaps[i].pattrs[j].attr.attr;
>> -			j++;
>> -		}
>> +		for (j = 0; j < ARRAY_SIZE(powercap_strs); j++) {
>> +			if (of_property_read_u32(node, powercap_strs[j], &id))
>> +				continue;
>>  
>> -		if (has_cur) {
>> -			powercap_add_attr(cur, "powercap-current",
>> +			powercap_add_attr(id, powercap_strs[j],
>>  					  &pcaps[i].pattrs[j]);
>> -			pcaps[i].pattrs[j].attr.attr.mode |= 0220;
>> -			pcaps[i].pattrs[j].attr.store = powercap_store;
>>  			pcaps[i].pg.attrs[j] = &pcaps[i].pattrs[j].attr.attr;
>> -			j++;
>>  		}
>>  
>>  		if (sysfs_create_group(powercap_kobj, &pcaps[i].pg)) {
>> -- 
>> 1.8.3.1
>