From: Guenter Roeck <linux@roeck-us.net>
To: zlukwins <zbigniew.lukwinski@linux.intel.com>
Cc: jae.hyun.yoo@linux.intel.com, lukasz.tuz@intel.com,
linux-hwmon@vger.kernel.org
Subject: Re: Maximum rate value of input power for pmbus device
Date: Wed, 8 Jul 2020 06:33:02 -0700 [thread overview]
Message-ID: <0e806aa6-657d-e09b-6444-4ba430dc041f@roeck-us.net> (raw)
In-Reply-To: <808c2d5c-e0d9-572c-a002-2a87430702c7@linux.intel.com>
On 7/8/20 3:50 AM, zlukwins wrote:
>
> On 6/29/20 6:59 PM, Guenter Roeck wrote:
>> +linux-hwmon@vger.kernel.org
>>
>> On Mon, Jun 29, 2020 at 08:31:11AM +0200, zlukwins wrote:
>>> Hi,
>>>
>>>
>>> I am OpenBMC FW developer working currently on some power measurement stuff.
>>>
>>> I would like to have maximum rated input power for pmubus device available
>>> in hwmon sysfs. This value is read by MFR_PIN_MAX command:
>>>
>>> /MFR_PIN_MAX//
>>> //The MFR_PIN_MIN command sets or retrieves the maximum rated value, in
>>> watts, of//
>>> //the input power./
>> Interesting typo in the PMBus specification. Yes, it really does associate
>> MFR_PIN_MIN - which doesn't seem to exist - with the maximum rated output
>> power.
>>> And I wondering which attribute shell be used to expose that value in sysfs.
>>> I went through documentation
>>> (https://www.kernel.org/doc/Documentation/hwmon/sysfs-interface) and found
>>> the following:
>>>
>>> power[1-*]_max Maximum power.
>>> Unit: microWatt
>>> RW
>>>
>>> But it looks like it is already occupied by PIN_OP_WARN_LIMIT.
>>>
>>> Maybe new attribute shall be used? If so how to call that?
>>>
>> None of the standard attributes reports (or is supposed to report) rated
>> values, so we can not just use any of those.
>>
>> Also, we can not just add a single attribute to handle this situation,
>> for the simple reason that there are many more similar attributes.
>> PMBus specifies (this is from version 1.3.1):
>>
>> MFR_VIN_MIN
>> MFR_VIN_MAX
>> MFR_IIN_MAX
>> MFR_PIN_MAX
>> MFR_VOUT_MIN
>> MFR_VOUT_MAX
>> MFR_IOUT_MAX
>> MFR_POUT_MAX
>> MFR_TAMBIENT_MAX
>> MFR_TAMBIENT_MIN
>> MFR_MAX_TEMP_{1,2.3}
>>
>> All those report rated values. I do see the need/desire for reporting such
>> information. The only real solution I can see is to add a new set of
>> attributes to the hwmon ABI. Something like:
>>
>> currentX_rated_min # for consistency
>> currentX_rated_max
>> inX_rated_min
>> inX_rated_max
>> powerX_rated_min # for consistency
>> powerX_rated_max
>> tempX_rated_min
>> tempX_rated_max
>> plus maybe, for consistency:
>> humidityX_rated_min
>> humidityX_rated_max
>>
>> Those would be read-only attributes.
>>
>> Thoughts, comments, feedback anyone ?
>>
>> Thanks,
>> Guenter
>
>
> I really like your proposition but I guess we need to wait few more days for the feedback.
>
> But have some questions here.
>
> What about potential next steps when we all agreed to follow that approach. Should documentation modification reach upstream repository first and then e.g. pmbus hwmon module implementation?
>
We'll need a series of patches. One to amend the documentation, one to add
the necessary code to the hwmon core (so that the core supports it with
the _with_info API), one to add support to the PMBus core, and one each
to add support to affected drivers.
Once this is all complete, the lm-sensors package should be updated
as well.
Guenter
next prev parent reply other threads:[~2020-07-08 13:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <ddcb240a-5444-ba46-ecdf-70350d27125f@linux.intel.com>
2020-06-29 16:59 ` Maximum rate value of input power for pmbus device Guenter Roeck
2020-07-08 10:50 ` zlukwins
2020-07-08 13:33 ` Guenter Roeck [this message]
2020-07-21 18:31 ` zlukwins
2020-07-21 19:54 ` Guenter Roeck
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