linux-kernel - Re: [PATCH] hwmon: (pmbus/ibm-cffps) Do not swap max_power

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Message-ID: <8433a40f-abbb-a0a9-9227-85363c2a9201@roeck-us.net>
Date:   Mon, 30 Aug 2021 14:05:53 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Eddie James <eajames@...ux.ibm.com>,
        Brandon Wyman <bjwyman@...il.com>
Cc:     linux-hwmon@...r.kernel.org, openbmc@...ts.ozlabs.org,
        Jean Delvare <jdelvare@...e.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (pmbus/ibm-cffps) Do not swap max_power_out

On 8/30/21 1:11 PM, Eddie James wrote:
> On Mon, 2021-08-30 at 08:34 -0700, Guenter Roeck wrote:
>> On 8/30/21 6:50 AM, Eddie James wrote:
>>> On Sat, 2021-08-28 at 08:52 -0700, Guenter Roeck wrote:
>>>> On Fri, Aug 27, 2021 at 11:04:33PM +0000, Brandon Wyman wrote:
>>>>> The bytes for max_power_out from the ibm-cffps devices do not
>>>>> need
>>>>> to be
>>>>> swapped.
>>>>>
>>>>> Signed-off-by: Brandon Wyman <bjwyman@...il.com>
>>>>
>>>> Eddie, can you confirm this ?
>>>
>>> This can't be true for all the power supplies supported by this
>>> driver,
>>> no. I think we need to check the version first. Brandon, I tested
>>> this
>>> on witherspoon (which is psu version 1) and get 3148 watts. If it's
>>> not
>>> swapped, that would be 19468 watts...
>>>
>>
>> Hmm. Eddie, can you also have a look at commit 9fed8fa99334 ("hwmon:
>> (pmbus/ibm-cffps) Fix write bits for LED control") ?
>> We need to make sure that it doesn't mess up some versions of this
>> PS.
> 
> That one looks correct to me. I believe older PSUs didn't enforce this
> so I didn't catch it, but I do see that the older specifications
> mention setting bit 6 to "allow write".
> 

Great, thanks a lot for checking.

Guenter