On Fri, Apr 29, 2022 at 05:53:32PM +0300, Dmitry Baryshkov wrote:
> On 29/04/2022 15:01, Ansuel Smith wrote:
> > Check if hw_parent is present before calculating the round_rate to
> > prevent kernel panic. On error -EINVAL is reported.
> >
> > Signed-off-by: Ansuel Smith <ansuelsmth@xxxxxxxxx>
>
> I see that other clock drivers do not perform this check. Which path leads
> to this oops?
>
This comes from qsdk patches so I apologize in advance about this.
Anyway I'm checking the code and krait-cc is the only user of
krait_div2_clk_ops. That user have as parent only hfpll_something that
is declared by gcc. Now hfpll can also be declared in dts with a
dedicated driver so I wonder if the problem is there in the case when
hfpll is declared in dts and is probed after krait-cc. This is not the
case for ipq8064 but I wonder if qsdk have other krait based device that
have a configuration with hfpll declared in dts.
In short you are right and in our current code the check is uselss and
I'm positive about dropping this patch but I do wonder if downstream
there is an actual use of this. Don't know how to proceed. Any hint?
> > ---
> > drivers/clk/qcom/clk-krait.c | 7 ++++++-
> > 1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/clk/qcom/clk-krait.c b/drivers/clk/qcom/clk-krait.c
> > index 90046428693c..6c367ad6506a 100644
> > --- a/drivers/clk/qcom/clk-krait.c
> > +++ b/drivers/clk/qcom/clk-krait.c
> > @@ -84,7 +84,12 @@ EXPORT_SYMBOL_GPL(krait_mux_clk_ops);
> > static long krait_div2_round_rate(struct clk_hw *hw, unsigned long rate,
> > unsigned long *parent_rate)
> > {
> > - *parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw), rate * 2);
> > + struct clk_hw *hw_parent = clk_hw_get_parent(hw);
> > +
> > + if (!hw_parent)
> > + return -EINVAL;
> > +
> > + *parent_rate = clk_hw_round_rate(hw_parent, rate * 2);
> > return DIV_ROUND_UP(*parent_rate, 2);
> > }
>
>
> --
> With best wishes
> Dmitry
--
Ansuel
