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

[Guenter Roeck]

On 8/11/21 4:25 PM, Chris Packham wrote:
> On 12/08/21 11:18 am, Guenter Roeck wrote:
> > On Wed, Aug 11, 2021 at 10:19:44PM +0000, Chris Packham wrote:
> > > 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@xxxxxxxxxxxxxxxxxxx>
> > > > > ---
> > > > >     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.
> > What a mess.
> *sigh* I know. I've also got another 2 BluTek supplies I haven't got
> round to dealing with yet.
> > This needs to be documented in the driver, including the
> > behavior if any of those attributes is written into.
>
> Mercifully these attributes are all read-only. So at least we don't have
> to deal with that.
Ok.

> It's probably not too late to return -ENXIO for the WARN_LIMITs and have
> lm-sensors display the rated_max (we also have a custom consumer of the
> sysfs API that I'd need to sort out).

That would indeed be much better if it works for you.

Thanks,
Guenter

> > Guenter
> >
> > > > Guenter
> > > >
> > > > >     		break;
> > > > >     	case PMBUS_POUT_OP_WARN_LIMIT:
> > > > >     		ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_MFR_POUT_MAX);
> > > > > --
> > > > > 2.32.0
> > > > >