Re: [PATCH v9,4/7] thermal: mediatek: Add LVTS driver for mt8192 thermal zones

[AngeloGioacchino Del Regno]

Il 15/09/22 18:58, Balsam CHIHI ha scritto:
> Hi Angelo,
>
> > > +static int soc_temp_lvts_read_temp(void *data, int *temperature)
> > > +{
> > > +     struct soc_temp_tz *lvts_tz = (struct soc_temp_tz *)data;
> > > +     struct lvts_data *lvts_data = lvts_tz->lvts_data;
> > > +     struct device *dev = lvts_data->dev;
> > > +     unsigned int msr_raw;
> > > +
> > > +     msr_raw = readl(lvts_data->reg[lvts_tz->id]) & MRS_RAW_MASK;
> > > +     if (msr_raw == 0) {
> > > +             /* Prevents a false critical temperature trap */
> > > +             *temperature = 0;
> > > +             dev_dbg(dev, "LVTS not yet ready\n");
> >
> > ...and you're not returning an error code, despite this function was called
> > while LVTS is still not ready? :-)
>
> if I add "return -ENAVAIL;" here, I will get the following errors on boot :
> [    0.292094] thermal thermal_zone0: failed to read out thermal zone (-119)
> [    0.293019] thermal thermal_zone1: failed to read out thermal zone (-119)
> [    0.294158] thermal thermal_zone6: failed to read out thermal zone (-119)
> [    0.295697] thermal thermal_zone9: failed to read out thermal zone (-119)
> [    0.296600] thermal thermal_zone10: failed to read out thermal zone (-119)
> [    0.297698] thermal thermal_zone15: failed to read out thermal zone (-119)
> [    0.298625] thermal thermal_zone16: failed to read out thermal zone (-119)
>
> I just preferred : *temperature = 0; to avoid a false critical temperature trap,
> and "return 0;" to suppress these errors.
> After that (first read at boot when LVTS is not fully ready),
> "msr_raw" will be always != 0.
> And I did not want to add a "delay" or a "sleep".
> Please let me know if you have any suggestions that could fix it in a
> better way.

It's the wrong error number. You have to return -EAGAIN :-)

> > > +
> > > +     } else
> > > +             *temperature = lvts_raw_to_temp(&lvts_data->coeff, msr_raw);
> > > +
> > > +     return 0;
> > > +}
>
> Best regards,
> Balsam