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: Tue, 21 Jul 2020 12:54:03 -0700 [thread overview]
Message-ID: <0d4a7ba3-6019-4737-5d99-24da45efdd81@roeck-us.net> (raw)
In-Reply-To: <2272b8d4-84fd-3c23-db38-23b6e61fe684@linux.intel.com>
On 7/21/20 11:31 AM, zlukwins wrote:
>
> On 7/8/20 3:33 PM, Guenter Roeck wrote:
>> 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
>
> Do you think we need to wait for feedback or maybe we could implement with your proposition? Maybe I could start working on patches?
>
I don't think we will get any further feedback. Please go ahead.
Thanks,
Guenter
>
> Thanks
>
> Zbigniew
>
prev parent reply other threads:[~2020-07-21 19:54 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
2020-07-21 18:31 ` zlukwins
2020-07-21 19:54 ` Guenter Roeck [this message]
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