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

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Date:   Mon, 31 Jul 2023 14:38:20 +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

On Fri, 28 Jul 2023 at 19:56, Guenter Roeck <linux@...ck-us.net> wrote:
>
> On 7/28/23 04:28, Naresh Solanki wrote:
> > 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.
>
> Please also add a comment that MP2975 is likely affected but can not be
> confirmed due to lack of a datasheet.
I have the datasheet for MP2975 but haven't verified it on real HW.

Regards,
Naresh
>
> Thanks,
> Guenter
>
> >>
> >>> 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
> >>
>