Re: [PATCH] mmc: mxs-mmc: Disable the 'reg_vmmc' regulator when needed

[Christophe JAILLET]

Le 24/05/2021 à 15:59, Ulf Hansson a écrit :
> On Fri, 21 May 2021 at 14:36, Christophe JAILLET
> <christophe.jaillet@xxxxxxxxxx> wrote:
> > The 'reg_vmmc' regulator is never disabled. Neither in the error handling
> > of the probe, nor in the remove function.
> >
> > Add a managed action to do the required clean-up before a 'regulator_put()'
> > call.
> >
> > Fixes: 4dc5a79f1350 ("mmc: mxs-mmc: enable regulator for mmc slot")
> > Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> > ---
> >   drivers/mmc/host/mxs-mmc.c | 11 +++++++++++
> >   1 file changed, 11 insertions(+)
> >
> > diff --git a/drivers/mmc/host/mxs-mmc.c b/drivers/mmc/host/mxs-mmc.c
> > index 947581de7860..b043d53dd728 100644
> > --- a/drivers/mmc/host/mxs-mmc.c
> > +++ b/drivers/mmc/host/mxs-mmc.c
> > @@ -552,6 +552,13 @@ static const struct of_device_id mxs_mmc_dt_ids[] = {
> >   };
> >   MODULE_DEVICE_TABLE(of, mxs_mmc_dt_ids);
> >
> > +static void regulator_disable_action(void *_data)
> > +{
> > +       struct regulator *regulator = _data;
> > +
> > +       regulator_disable(regulator);
> > +}
> > +
> >   static int mxs_mmc_probe(struct platform_device *pdev)
> >   {
> >          struct device_node *np = pdev->dev.of_node;
> > @@ -591,6 +598,10 @@ static int mxs_mmc_probe(struct platform_device *pdev)
> >                                  "Failed to enable vmmc regulator: %d\n", ret);
> >                          goto out_mmc_free;
> >                  }
> > +               ret = devm_add_action_or_reset(&pdev->dev,
> > +                                       regulator_disable_action, reg_vmmc);
> > +               if (ret)
> > +                       goto out_mmc_free;
>
> Even if this improves the behaviour, there is a standardized way for
> how we deal with regulators for mmc.
>
> 1. Call mmc_regulator_get_supply() during probe to fetch the optional
> regulator. If a regulator is found a corresponding OCR mask, in
> host->ocr_avail is assigned.
>
> 2. In the ->set_ios() callback, invoke mmc_regulator_set_ocr(). This
> will also set the correct voltage-level and turn on/off the regulator,
> depending on the requested OCR/voltage-level.

Hi,
I don't know this API.
I've tried to look at a few drivers to see how it was used, but it 
didn't help me either.

So, I won't be able to provide any other proposal on this. It would only 
be trial/error.
It is yours if something needs to be fixed here.

Anyway, thanks for your time for answering and trying to show the right 
direction.

CJ

> >          }
> >
> >          ssp->clk = devm_clk_get(&pdev->dev, NULL);
> > --
> > 2.30.2
>
> Kind regards
> Uffe