linux-kernel - Re: [PATCH] hwmon: (pmbus/mp2975) Fix PGOOD in READ_STATUS

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Date:   Fri, 28 Jul 2023 16:58:35 +0530
From:   Naresh Solanki <naresh.solanki@...ements.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Jean Delvare <jdelvare@...e.com>,
        krzysztof.kozlowski+dt@...aro.org, linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (pmbus/mp2975) Fix PGOOD in READ_STATUS_WORD

Hi Guenter,


On Fri, 28 Jul 2023 at 15:30, Guenter Roeck <linux@...ck-us.net> wrote:
>
> On 7/28/23 01:25, Naresh Solanki wrote:
> > From: Patrick Rudolph <patrick.rudolph@...ements.com>
> >
> > MPS returns PGOOD instead of PB_STATUS_POWER_GOOD_N.
> > Fix that in the read_word_data hook.
> >
> Datasheets are not public, so I can not verify, but the code below
> only handles MP2973 and MP2971. What about MP2975 ?
I dont have MP2975 to even verify. I'm not sure if its applicable.
>
> Either case, this appears to affect most Monolithic chips, but
> not all of them. Please limit the statement to known to be affected
> chips.
Yes. With what we observed, this affects mp2973 & mp2971.
Will update accordingly.
>
> > Signed-off-by: Patrick Rudolph <patrick.rudolph@...ements.com>
> > Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
> > ---
> >   drivers/hwmon/pmbus/mp2975.c | 4 ++++
> >   1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/hwmon/pmbus/mp2975.c b/drivers/hwmon/pmbus/mp2975.c
> > index 28f33f4618fa..410b6eae6d02 100644
> > --- a/drivers/hwmon/pmbus/mp2975.c
> > +++ b/drivers/hwmon/pmbus/mp2975.c
> > @@ -297,6 +297,10 @@ static int mp2973_read_word_data(struct i2c_client *client, int page,
> >       int ret;
> >
> >       switch (reg) {
> > +     case PMBUS_STATUS_WORD:
> > +             ret = pmbus_read_word_data(client, page, phase, reg);
>
>                 if (ret < 0)
>                         return ret;
>
> Please add a comment explaining what is going on.
Sure.
>
> > +             ret ^= PB_STATUS_POWER_GOOD_N;
> > +             break;
> >       case PMBUS_OT_FAULT_LIMIT:
> >               ret = mp2975_read_word_helper(client, page, phase, reg,
> >                                             GENMASK(7, 0));
> >
> > base-commit: a4bb1ce5b9e3ca403c04e20ebeae77fd6447cb11
>