linux-kernel - Re: [PATCH 1/2] hwmon: (pmbus/bpa-rs600) Remove duplicate defininitions

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Date:   Wed, 11 Aug 2021 21:58:09 +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 1/2] hwmon: (pmbus/bpa-rs600) Remove duplicate
 defininitions


On 12/08/21 7:53 am, Guenter Roeck wrote:
> On Wed, Aug 11, 2021 at 04:17:37PM +1200, Chris Packham wrote:
>> Commit 787c095edaa9 ("hwmon: (pmbus/core) Add support for rated
>> attributes") added definitions for MFR_VIN_MIN etc so we can remove the
>> local definitions of these from the bpa-rs600 driver.
>>
>> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
>> ---
>>   drivers/hwmon/pmbus/bpa-rs600.c | 25 ++++++++-----------------
>>   1 file changed, 8 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/hwmon/pmbus/bpa-rs600.c b/drivers/hwmon/pmbus/bpa-rs600.c
>> index d205b41540ce..d495faa89799 100644
>> --- a/drivers/hwmon/pmbus/bpa-rs600.c
>> +++ b/drivers/hwmon/pmbus/bpa-rs600.c
>> @@ -12,15 +12,6 @@
>>   #include <linux/pmbus.h>
>>   #include "pmbus.h"
>>   
>> -#define BPARS600_MFR_VIN_MIN	0xa0
>> -#define BPARS600_MFR_VIN_MAX	0xa1
>> -#define BPARS600_MFR_IIN_MAX	0xa2
>> -#define BPARS600_MFR_PIN_MAX	0xa3
>> -#define BPARS600_MFR_VOUT_MIN	0xa4
>> -#define BPARS600_MFR_VOUT_MAX	0xa5
>> -#define BPARS600_MFR_IOUT_MAX	0xa6
>> -#define BPARS600_MFR_POUT_MAX	0xa7
>> -
>>   enum chips { bpa_rs600, bpd_rs600 };
>>   
>>   static int bpa_rs600_read_byte_data(struct i2c_client *client, int page, int reg)
>> @@ -83,28 +74,28 @@ static int bpa_rs600_read_word_data(struct i2c_client *client, int page, int pha
>>   
>>   	switch (reg) {
>>   	case PMBUS_VIN_UV_WARN_LIMIT:
>> -		ret = pmbus_read_word_data(client, 0, 0xff, BPARS600_MFR_VIN_MIN);
>> +		ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_VIN_MIN);
>>   		break;
>>   	case PMBUS_VIN_OV_WARN_LIMIT:
>> -		ret = pmbus_read_word_data(client, 0, 0xff, BPARS600_MFR_VIN_MAX);
>> +		ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_VIN_MAX);
>>   		break;
>>   	case PMBUS_VOUT_UV_WARN_LIMIT:
>> -		ret = pmbus_read_word_data(client, 0, 0xff, BPARS600_MFR_VOUT_MIN);
>> +		ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_VOUT_MIN);
>>   		break;
>>   	case PMBUS_VOUT_OV_WARN_LIMIT:
>> -		ret = pmbus_read_word_data(client, 0, 0xff, BPARS600_MFR_VOUT_MAX);
>> +		ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_VOUT_MAX);
>>   		break;
>>   	case PMBUS_IIN_OC_WARN_LIMIT:
>> -		ret = pmbus_read_word_data(client, 0, 0xff, BPARS600_MFR_IIN_MAX);
>> +		ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_IIN_MAX);
>>   		break;
>>   	case PMBUS_IOUT_OC_WARN_LIMIT:
>> -		ret = pmbus_read_word_data(client, 0, 0xff, BPARS600_MFR_IOUT_MAX);
>> +		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, BPARS600_MFR_PIN_MAX);
>> +		ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_PIN_MAX);
>>   		break;
>>   	case PMBUS_POUT_OP_WARN_LIMIT:
>> -		ret = pmbus_read_word_data(client, 0, 0xff, BPARS600_MFR_POUT_MAX);
>> +		ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_POUT_MAX);
> If the above is correct, the driver reports the wrong attributes. For example,
> PMBUS_MFR_PIN_MAX is supposed to report the rated limit, not the warning limit.
> What does the datasheet say ?

The datasheet doesn't list PMBUS_VIN_UV_WARN_LIMIT etc at all. It does 
say that MFR_VIN_xxx is the "rated" value but in my testing this also 
appears that this is the same threshold at which the ALERT pin is asserted.

When I did the initial implementation I decided to map the WARN_LIMITs 
to what I thought were reasonable manufacturer specific equivalents. 
This also means that the thresholds can be displayed by existing 
userspace tools that consume the sysfs ABI.

> Guenter
>
>>   		break;
>>   	case PMBUS_VIN_UV_FAULT_LIMIT:
>>   	case PMBUS_VIN_OV_FAULT_LIMIT:
>> -- 
>> 2.32.0
>>