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

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Message-ID: <e95c8f49-53ea-9319-43e7-3a05f335a0b2@gmail.com>
Date:   Tue, 31 Aug 2021 15:18:29 -0500
From:   Brandon Wyman <bjwyman@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Eddie James <eajames@...ux.ibm.com>
Cc:     Joel Stanley <joel@....id.au>, openbmc@...ts.ozlabs.org,
        Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (pmbus/ibm-cffps) Do not swap max_power_out


On 2021-08-30 16:27, Guenter Roeck wrote:
> On 8/30/21 2:07 PM, Brandon Wyman wrote:
>>
>> On 2021-08-30 08:50, 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...
>>>
>>> Thanks,
>>> Eddie
>> I had tested this on a variety of systems with a variety of different 
>> power supplies, but I did *NOT* test this on the Witherspoon power 
>> supplies.
>>
>> This apparently requires a bit more thought to figure out how to 
>> handle the other types and also not get Witherspoon wrong.
>>
>
> Is the specification for those power supplies available in public ?
>
> Thanks,
> Guenter
>
No, unfortunately those power supply specifications are not available to 
the public.

Sorry,

Brandon

>> Thanks for checking Eddie.
>>
>>>> Thanks,
>>>> Guenter
>>>>
>>>>> ---
>>>>>   drivers/hwmon/pmbus/ibm-cffps.c | 2 +-
>>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/hwmon/pmbus/ibm-cffps.c
>>>>> b/drivers/hwmon/pmbus/ibm-cffps.c
>>>>> index df712ce4b164..29b77f192c9e 100644
>>>>> --- a/drivers/hwmon/pmbus/ibm-cffps.c
>>>>> +++ b/drivers/hwmon/pmbus/ibm-cffps.c
>>>>> @@ -171,7 +171,7 @@ static ssize_t ibm_cffps_debugfs_read(struct
>>>>> file *file, char __user *buf,
>>>>>           cmd = CFFPS_SN_CMD;
>>>>>           break;
>>>>>       case CFFPS_DEBUGFS_MAX_POWER_OUT:
>>>>> -        rc = i2c_smbus_read_word_swapped(psu->client,
>>>>> +        rc = i2c_smbus_read_word_data(psu->client,
>>>>>                            CFFPS_MAX_POWER_OUT_CM
>>>>> D);
>>>>>           if (rc < 0)
>>>>>               return rc;
>>>>> -- 
>>>>> 2.25.1
>>>>>
>