linux-kernel - Re: [PATCH v2] hwmon: (pmbus/ibm-cffps) Add clear

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Message-ID: <CAK_vbW2S07+S8+PrQnBLjvXYnLBXU06FHBvfM2zaT6RYx9HO+g@mail.gmail.com>
Date:   Wed, 16 Mar 2022 15:03:05 -0500
From:   Brandon Wyman <bjwyman@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Joel Stanley <joel@....id.au>,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
        Eddie James <eajames@...ux.ibm.com>,
        Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] hwmon: (pmbus/ibm-cffps) Add clear_faults debugfs entry

On Sun, Mar 13, 2022 at 11:36 PM Guenter Roeck <linux@...ck-us.net> wrote:
>
> On 3/11/22 10:10, Brandon Wyman wrote:
> > Add a clear_faults write-only debugfs entry for the ibm-cffps device
> > driver.
> >
> > Certain IBM power supplies require clearing some latched faults in order
> > to indicate that the fault has indeed been observed/noticed.
> >
>
> That is insufficient, sorry. Please provide the affected power supplies as
> well as the affected faults, and confirm that the problem still exists
> in v5.17-rc6 or later kernels - or, more specifically, in any kernel which
> includes commit 35f165f08950 ("hwmon: (pmbus) Clear pmbus fault/warning
> bits after read").
>
> Thanks,
> Guenter

Sorry for the delay in responding. I did some testing with commit
35f165f08950. I could not get that code to send the CLEAR_FAULTS
command to the power supplies.

I can update the commit message to be more specific about which power
supplies need this CLEAR_FAULTS sent, and which faults. It is observed
with the 1600W power supplies (2B1E model). The faults that latch are
the VIN_UV and INPUT faults in the STATUS_WORD. The corresponding
STATUS_INPUT fault bits are VIN_UV_FAULT and Unit is Off.

>
> > Signed-off-by: Brandon Wyman <bjwyman@...il.com>
> > ---
> > V1 -> V2: Explain why this change is needed
> >
> >   drivers/hwmon/pmbus/ibm-cffps.c | 11 +++++++++++
> >   1 file changed, 11 insertions(+)
> >
> > diff --git a/drivers/hwmon/pmbus/ibm-cffps.c b/drivers/hwmon/pmbus/ibm-cffps.c
> > index e3294a1a54bb..3f02dde02a4b 100644
> > --- a/drivers/hwmon/pmbus/ibm-cffps.c
> > +++ b/drivers/hwmon/pmbus/ibm-cffps.c
> > @@ -67,6 +67,7 @@ enum {
> >       CFFPS_DEBUGFS_CCIN,
> >       CFFPS_DEBUGFS_FW,
> >       CFFPS_DEBUGFS_ON_OFF_CONFIG,
> > +     CFFPS_DEBUGFS_CLEAR_FAULTS,
> >       CFFPS_DEBUGFS_NUM_ENTRIES
> >   };
> >
> > @@ -274,6 +275,13 @@ static ssize_t ibm_cffps_debugfs_write(struct file *file,
> >               if (rc)
> >                       return rc;
> >
> > +             rc = 1;
> > +             break;
> > +     case CFFPS_DEBUGFS_CLEAR_FAULTS:
> > +             rc = i2c_smbus_write_byte(psu->client, PMBUS_CLEAR_FAULTS);
> > +             if (rc < 0)
> > +                     return rc;
> > +
> >               rc = 1;
> >               break;
> >       default:
> > @@ -607,6 +615,9 @@ static int ibm_cffps_probe(struct i2c_client *client)
> >       debugfs_create_file("on_off_config", 0644, ibm_cffps_dir,
> >                           &psu->debugfs_entries[CFFPS_DEBUGFS_ON_OFF_CONFIG],
> >                           &ibm_cffps_fops);
> > +     debugfs_create_file("clear_faults", 0200, ibm_cffps_dir,
> > +                         &psu->debugfs_entries[CFFPS_DEBUGFS_CLEAR_FAULTS],
> > +                         &ibm_cffps_fops);
> >
> >       return 0;
> >   }
>