linux-kernel - Re: [PATCH v3 1/2] hwmon: (pmbus) Add Delta AHE-50DC fan control module driver

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Date:   Tue, 7 Dec 2021 16:41:02 -0800
From:   Zev Weiss <zev@...ilderbeest.net>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     linux-hwmon@...r.kernel.org, Jean Delvare <jdelvare@...e.com>,
        openbmc@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/2] hwmon: (pmbus) Add Delta AHE-50DC fan control
 module driver

On Tue, Dec 07, 2021 at 03:15:18PM PST, Guenter Roeck wrote:
>On 12/7/21 1:53 PM, Zev Weiss wrote:
>>On Tue, Dec 07, 2021 at 11:44:01AM PST, Guenter Roeck wrote:
>>>On 12/7/21 11:22 AM, Zev Weiss wrote:
>>>>On Tue, Dec 07, 2021 at 09:50:15AM PST, Guenter Roeck wrote:
>>>>>On Mon, Dec 06, 2021 at 11:15:20PM -0800, Zev Weiss wrote:
>>>>>>This device is an integrated module of the Delta AHE-50DC Open19 power
>>>>>>shelf.  For lack of proper documentation, this driver has been developed
>>>>>>referencing an existing (GPL) driver that was included in a code release
>>>>>>from LinkedIn [1].  It provides four fan speeds, four temperatures, and
>>>>>>one voltage reading, as well as a handful of warning and fault
>>>>>>indicators.
>>>>>>
>>>>>>[1] https://github.com/linkedin/o19-bmc-firmware/blob/master/meta-openbmc/meta-linkedin/meta-deltapower/recipes-kernel/fancontrol-mod/files/fancontrol.c
>>>>>>
>>>>>
>>>>>Hmm, that reference isn't really accurate anymore. I think it would be
>>>>>better to just say that the device was found to be PMBus compliant.
>>>>
>>>>Sure, will do.
>>>>
>>>
>>>Makes me wonder: How do you know that the referenced driver is for Delta AHE-50DC ?
>>
>>We'd been waiting for the source code for the software it ships with for a while, and were finally provided with that repo; everything I've observed from the factory software is consistent with the code in that driver.  A sampling:
>>
>
>I assume you mean "Delta AHE-50DC" when you refer to "it".
>

Yes.

>[ ... ]
>>>Can you check this with real hardware, by any chance ?
>>>
>>
>>If you mean running that code on it, yes -- here's the userspace utility that invokes that library routine:
>>
>>     root@...-oob:~# fan-util.sh
>>     fan1 speed: 7860 RPM
>>     fan2 speed: 7860 RPM
>>     fan3 speed: 7620 RPM
>>     fan4 speed: 7560 RPM
>>     temperature1: 29.20 C
>>     temperature2: 27.80 C
>>     temperature3: 28.50 C
>>     temperature4: 30.20 C
>>     vin_undervolt_fault: no
>>     overtemperature_warning: no
>>     fan_fault: no
>>     fan_warning: no
>>     fan_status: ok
>>
>
>That doesn't really tell me anything in the context of the driver you submitted.
>Would it be possible to install your driver and provide the output from the
>"sensors" command ? It should match the information from the proprietary
>driver/tool.
>

Thanks, in doing so I realized I'd neglected to prevent reads from 
unsupported registers in the read_word_data function, which was leading 
to the driver producing sysfs files for meaningless sensor limits that 
the device doesn't actually support.  With that fix (which I'll include 
in v4):

     root@...-50dc:~# /tmp/sensors 'ahe50dc_fan-*'
     ahe50dc_fan-i2c-28-30
     Adapter: i2c-8-mux (chan_id 0)
     vin:          12.29 V  
     fan1:        7680 RPM
     fan2:        7860 RPM
     fan3:        7680 RPM
     fan4:        7380 RPM
     temp1:        +27.8 C  
     temp2:        +23.4 C  
     temp3:        +25.3 C  
     temp4:        +24.5 C  



Zev