Re: [PATCH v4] i2c: npcm: Add clock toggle recovery

[Mohammed Elbadry]

Hi Andi,

On Sun, Apr 13, 2025 at 4:06 PM Andi Shyti <andi.shyti@xxxxxxxxxx> wrote:
>
> Hi Mohammed,
>
> On Fri, Mar 28, 2025 at 07:32:50PM +0000, mohammed.0.elbadry@xxxxxxxxx wrote:
> > From: Tali Perry <tali.perry1@xxxxxxxxx>
> >
> > During init of the bus, the module checks that the bus is idle.
> > If one of the lines are stuck try to recover them first before failing.
> > Sometimes SDA and SCL are low if improper reset occurs (e.g., reboot).
> >
> > Signed-off-by: Tali Perry <tali.perry1@xxxxxxxxx>
> > Signed-off-by: Mohammed Elbadry <mohammed.0.elbadry@xxxxxxxxx>
> > ---
>
> we are missing the changelog here. You are at v4 and I need to
> see the changes between the versions. For now it's OK, please,
> next time don't forget to add the changelog.
I understand, I will do that, thank you.

>
> One more thing, no need to send patches as --in-reply-to your
> previous patch.
>
> >  drivers/i2c/busses/i2c-npcm7xx.c | 12 ++++++++----
> >  1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-npcm7xx.c b/drivers/i2c/busses/i2c-npcm7xx.c
> > index 2fe68615942e..caf9aa1e6319 100644
> > --- a/drivers/i2c/busses/i2c-npcm7xx.c
> > +++ b/drivers/i2c/busses/i2c-npcm7xx.c
> > @@ -1967,10 +1967,14 @@ static int npcm_i2c_init_module(struct npcm_i2c *bus, enum i2c_mode mode,
> >
> >       /* Check HW is OK: SDA and SCL should be high at this point. */
> >       if ((npcm_i2c_get_SDA(&bus->adap) == 0) || (npcm_i2c_get_SCL(&bus->adap) == 0)) {
> > -             dev_err(bus->dev, "I2C%d init fail: lines are low\n", bus->num);
> > -             dev_err(bus->dev, "SDA=%d SCL=%d\n", npcm_i2c_get_SDA(&bus->adap),
> > -                     npcm_i2c_get_SCL(&bus->adap));
> > -             return -ENXIO;
> > +             dev_warn(bus->dev, " I2C%d SDA=%d SCL=%d, attempting to recover\n", bus->num,
>
> the space at the beginning of the line should be removed. I will
> take care of it if you won't be asked to send a new version.
>
Got it, thank you.
> > +                              npcm_i2c_get_SDA(&bus->adap), npcm_i2c_get_SCL(&bus->adap));
> > +             if (npcm_i2c_recovery_tgclk(&bus->adap)) {
> > +                     dev_err(bus->dev, "I2C%d init fail: SDA=%d SCL=%d\n",
> > +                             bus->num, npcm_i2c_get_SDA(&bus->adap),
> > +                             npcm_i2c_get_SCL(&bus->adap));
> > +                     return -ENXIO;
>
> why don't we return the error coming from
> npcm_i2c_recovery_tgclk() instead of forcing it to ENXIO?

The error that comes from the current driver is only -ENOTRECOVERABLE.
I do not see why we cannot return that error instead. I understand the
difference between both states; however, from the driver's
perspective, on initialization, ENXIO and ENOTRECOVERABLE behavior is
identical in that state.

ENXIO was what the driver returned by default without trying to
recover. Do you recommend changing it? Let me know. I am happy to send
the v5 patch with the change and address the above comments, too.

Thank you,
Mo
>
> Thanks,
> Andi
>
> > +             }
> >       }
> >
> >       npcm_i2c_int_enable(bus, true);
> > --
> > 2.49.0.472.ge94155a9ec-goog
> >