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

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Date:   Mon, 30 Aug 2021 16:07:41 -0500
From:   Brandon Wyman <bjwyman@...il.com>
To:     Eddie James <eajames@...ux.ibm.com>,
        Guenter Roeck <linux@...ck-us.net>
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 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.

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
>>>