Re: [PATCH v1 4/4] PM / devfreq: tegra30: Check whether clk_round_rate() returns zero rate

[Chanwoo Choi]

On 21. 9. 16. 오전 10:28, Dmitry Osipenko wrote:
> 15.09.2021 21:31, Chanwoo Choi пишет:
> > On 21. 9. 15. 오후 12:51, Chanwoo Choi wrote:
> > > Hi,
> > >
> > > On 21. 9. 13. 오전 3:44, Dmitry Osipenko wrote:
> > > > EMC clock is always-on and can't be zero. Check whether clk_round_rate()
> > > > returns zero rate and error out if it does. It can return zero if clock
> > > > tree isn't initialized properly.
> > > >
> > > > Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> > > > ---
> > > >    drivers/devfreq/tegra30-devfreq.c | 4 ++--
> > > >    1 file changed, 2 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/devfreq/tegra30-devfreq.c
> > > > b/drivers/devfreq/tegra30-devfreq.c
> > > > index d83fdc2713ed..65ecf17a36f4 100644
> > > > --- a/drivers/devfreq/tegra30-devfreq.c
> > > > +++ b/drivers/devfreq/tegra30-devfreq.c
> > > > @@ -891,9 +891,9 @@ static int tegra_devfreq_probe(struct
> > > > platform_device *pdev)
> > > >            return err;
> > > >        rate = clk_round_rate(tegra->emc_clock, ULONG_MAX);
> > > > -    if (rate < 0) {
> > > > +    if (rate <= 0) {
> > > >            dev_err(&pdev->dev, "Failed to round clock rate: %ld\n",
> > > > rate);
> > > > -        return rate;
> > > > +        return rate ?: -EINVAL;
> >
> > If rate is 0, It doesn't return and fall-through? even if print the
> > error message. 'return rate ?: -EINVAL;' style is strange for me
> > because it doesn't specify the 'return value' when rate is true.
>
> It's not clear to me what do you mean by "return and fall-through".
>
> It specifies the 'return value' when rate is true. It's a short form of
> "rate ? rate : -EINVAL".

I has not known this short form. Thanks for comment. I understand.



--
Best Regards,
Samsung Electronics
Chanwoo Choi