linux-kernel - Re: [PATCH 2/2] hwmon: (pmbus/bpa-rs600) Add workaround for incorrect Pin max

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Date:   Wed, 11 Aug 2021 22:19:44 +0000
From:   Chris Packham <Chris.Packham@...iedtelesis.co.nz>
To:     Guenter Roeck <linux@...ck-us.net>
CC:     "jdelvare@...e.com" <jdelvare@...e.com>,
        "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] hwmon: (pmbus/bpa-rs600) Add workaround for incorrect
 Pin max


On 12/08/21 7:53 am, Guenter Roeck wrote:
> On Wed, Aug 11, 2021 at 04:17:38PM +1200, Chris Packham wrote:
>> BPD-RS600 modules running firmware v5.70 misreport the MFR_PIN_MAX.
>> The indicate a maximum of 1640W instead of 700W. Detect the invalid
>> reading and return a sensible value instead.
>>
>> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
>> ---
>>   drivers/hwmon/pmbus/bpa-rs600.c | 21 ++++++++++++++++++++-
>>   1 file changed, 20 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/hwmon/pmbus/bpa-rs600.c b/drivers/hwmon/pmbus/bpa-rs600.c
>> index d495faa89799..f4baed9ce8a4 100644
>> --- a/drivers/hwmon/pmbus/bpa-rs600.c
>> +++ b/drivers/hwmon/pmbus/bpa-rs600.c
>> @@ -65,6 +65,24 @@ static int bpa_rs600_read_vin(struct i2c_client *client)
>>   	return ret;
>>   }
>>   
>> +/*
>> + * The firmware on some BPD-RS600 models incorrectly reports 1640W
>> + * for MFR_PIN_MAX. Deal with this by returning a sensible value.
>> + */
>> +static int bpa_rs600_read_pin_max(struct i2c_client *client)
>> +{
>> +	int ret;
>> +
>> +	ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_PIN_MAX);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	if (ret == 0x0b34)
>> +		return 0x095e;
> The comments from the descriotion need to be here.
will update
> Thanks,
> Guenter
>
>> +
>> +	return ret;
>> +}
>> +
>>   static int bpa_rs600_read_word_data(struct i2c_client *client, int page, int phase, int reg)
>>   {
>>   	int ret;
>> @@ -92,7 +110,8 @@ static int bpa_rs600_read_word_data(struct i2c_client *client, int page, int pha
>>   		ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_IOUT_MAX);
>>   		break;
>>   	case PMBUS_PIN_OP_WARN_LIMIT:
>> -		ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_PIN_MAX);
>> +	case PMBUS_MFR_PIN_MAX:
>> +		ret = bpa_rs600_read_pin_max(client);
> So the idea is to return the same value for PMBUS_PIN_OP_WARN_LIMIT
> (max_alarm) and PMBUS_MFR_PIN_MAX (rated_max) ? That doesn't really
> make sense. The meaning of those limits is distinctly different.
For the BPA-RS600/BPD-RS600 these appear to be treated the same.
>
> Guenter
>
>>   		break;
>>   	case PMBUS_POUT_OP_WARN_LIMIT:
>>   		ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_POUT_MAX);
>> -- 
>> 2.32.0
>>