[PATCH 4/6] rtc: sun6i: Force the mux to the external oscillator

[Alexandre Belloni]

On 21/01/2017 at 11:53:08 +0800, Chen-Yu Tsai wrote :
> Hi,
> 
> On Fri, Jan 20, 2017 at 11:56 PM, Maxime Ripard
> <maxime.ripard at free-electrons.com> wrote:
> > The internal oscillator is way too inaccurate to do something useful with
> > it. Switch to the external oscillator if it is available.
> >
> > Signed-off-by: Maxime Ripard <maxime.ripard at free-electrons.com>
> > ---
> >  drivers/rtc/rtc-sun6i.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
> > index edd5627da10f..1695fae24cd5 100644
> > --- a/drivers/rtc/rtc-sun6i.c
> > +++ b/drivers/rtc/rtc-sun6i.c
> > @@ -493,6 +493,7 @@ static const struct rtc_class_ops sun6i_rtc_ops = {
> >  static int sun6i_rtc_probe(struct platform_device *pdev)
> >  {
> >         struct sun6i_rtc_dev *chip = sun6i_rtc;
> > +       struct clk *parent;
> >         int ret;
> >
> >         if (!chip)
> > @@ -540,6 +541,17 @@ static int sun6i_rtc_probe(struct platform_device *pdev)
> >         /* disable alarm wakeup */
> >         writel(0, chip->base + SUN6I_ALARM_CONFIG);
> >
> > +       parent = clk_get(&pdev->dev, NULL);
> > +       if (!IS_ERR(parent)) {
> > +               ret = clk_set_parent(chip->losc, parent);
> > +               clk_put(parent);
> > +
> > +               if (ret) {
> > +                       dev_err(&pdev->dev,
> > +                               "Failed to reparent the RTC to the external oscillator\n");
> > +                       return ret;
> > +               }
> > +       }
> 
> Following what I mentioned in patch 1, maybe it is easier to force
> the mux before the clocks are registered by writing directly to
> the registers? We could also backport the changes to stable?
> 

I'd say that the risk to break existing platforms is low enough to
backport that patch to stable.
Maxime as you are certainly the one that will handle the potential
breakage, I'll let you choose what you want to do.


-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com