Re: [RFC v3 04/10] OPP: Add and export helper to update voltage

[Sibi Sankar]

On 2020-01-29 03:03, Matthias Kaehlcke wrote:
> Hi Sibi,
>
> On Tue, Jan 28, 2020 at 01:33:44AM +0530, Sibi Sankar wrote:
> > Add and export 'dev_pm_opp_update_voltage' to find and update voltage
> > of an opp for a given frequency. This will be useful to update the 
> > opps
> > with voltages read back from firmware.
> >
> > Signed-off-by: Sibi Sankar <sibis@xxxxxxxxxxxxxx>
> > ---
> >  drivers/opp/core.c     | 55 
> > ++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/pm_opp.h | 10 ++++++++
> >  2 files changed, 65 insertions(+)
> >
> > diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> > index 9aa2a44a5d638..f241e83ec926a 100644
> > --- a/drivers/opp/core.c
> > +++ b/drivers/opp/core.c
> > @@ -2503,6 +2503,61 @@ int dev_pm_opp_disable(struct device *dev, 
> > unsigned long freq)
> >  }
> >  EXPORT_SYMBOL_GPL(dev_pm_opp_disable);
> >
> > +/**
> > + * dev_pm_opp_update_voltage() - Find and update voltage
>
> The comment should mention that this is done for an OPP.
>
> Maybe omit the 'find' part here and just say 'Update the voltage of
> an OPP'?

sure makes sense

> > + * @dev:	device for which we do this operation
> > + * @freq:	OPP frequency to update voltage
> > + * @u_volt:	voltage requested for this opp
> > + *
> > + * Find and update voltage of a disabled opp corresponding to the 
> > given
> > + * frequency. This is useful only for devices with single power 
> > supply.
> > + *
> > + * Return: 0 if modification was successful or a negative error 
> > value.
> > + */
> > +int dev_pm_opp_update_voltage(struct device *dev, unsigned long freq,
> > +			      unsigned long u_volt)
> > +{
> > +	struct dev_pm_opp *opp = ERR_PTR(-ENODEV);
>
> initialization is not needed
>
> > +	struct opp_table *opp_table;
> > +	unsigned long tol;
> > +	int ret = 0;
> > +
> > +	/* Find the opp_table */
>
> Drop the comment, it's obvious from the code.
>
> > +	opp_table = _find_opp_table(dev);
> > +	if (IS_ERR(opp_table)) {
> > +		ret = PTR_ERR(opp_table);
> > +		dev_err(dev, "%s: OPP table not found (%d)\n", __func__, ret);
> > +		return PTR_ERR(opp_table);
>
>   		return ret;

missed that :(

> > +	}
> > +
> > +	opp = dev_pm_opp_find_freq_exact(dev, freq, false);
> > +	if (IS_ERR(opp)) {
> > +		ret = PTR_ERR(opp);
> > +		goto put_table;
> > +	}
> > +
> > +	mutex_lock(&opp_table->lock);
> > +
> > +	/* update only if the opp is disabled */
> > +	if (opp->available) {
> > +		ret = -EBUSY;
> > +		goto unlock;
> > +	}
> > +
> > +	tol = u_volt * opp_table->voltage_tolerance_v1 / 100;
> > +	opp->supplies[0].u_volt_min = u_volt - tol;
> > +	opp->supplies[0].u_volt = u_volt;
> > +	opp->supplies[0].u_volt_min = u_volt + tol;
>
>   			.u_volt_max =
>
> I suppose the assignments need to be done for all possible supplies,
> i.e. 0 to (opp_table->regulator_count - 1).

a single value for all possible
supplies seems wrong. Anyway
will wait to see what Viresh
thinks about it.

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