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: Mon, 29 Jun 2020 09:59:50 -0700 [thread overview]
Message-ID: <20200629165950.GB113813@roeck-us.net> (raw)
In-Reply-To: <ddcb240a-5444-ba46-ecdf-70350d27125f@linux.intel.com>
+ 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
next parent reply other threads:[~2020-06-29 19:27 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 ` Guenter Roeck [this message]
2020-07-08 10:50 ` Maximum rate value of input power for pmbus device zlukwins
2020-07-08 13:33 ` Guenter Roeck
2020-07-21 18:31 ` zlukwins
2020-07-21 19:54 ` Guenter Roeck
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