[PATCH V2] clk: Add composite clock type

Tomasz Figa
2013-02-06T10:02:14Z

On Wednesday 06 of February 2013 15:22:54 Prashant Gaikwad wrote:
> On Wednesday 06 February 2013 11:40 AM, Hiroshi Doyu wrote:
> > Prashant Gaikwad <pgaikwad@nvidia.com> wrote @ Wed, 6 Feb 2013
03:55:00 +0100:
> >>>> No, clk_ops depends on the clocks you are using. There could be a
> >>>> clock
> >>>> with mux and gate while another one with mux and div.
> >>>
> >>> You are right. What about the following? We don't have to have
> >>> similar
> >>> copy of clk_composite_ops for each instances.
> >>
> >> Clock framework takes decision depending on the ops availability and
> >> it
> >> does not know if the clock is mux or gate.
> >>
> >> For example,
> >>
> >> if (clk->ops->enable) {
> >>
> >> ret = clk->ops->enable(clk->hw);
> >> if (ret) {
> >>
> >> __clk_disable(clk->parent);
> >> return ret;
> >>
> >> }
> >>
> >> }
> >>
> >> in above case if clk_composite does not have gate clock then as per
> >> your suggestion if it returns error value then it will fail and it
> >> is wrong.>
> > Ok, now I understand. Thank you for explanation.
> >
> > We always need to allocate clk_composite_ops for each clk_composite,
> > right? If so what about having "struct clk_ops ops" in "struct
> > clk_composite"?
> >
> > diff --git a/drivers/clk/clk-composite.c b/drivers/clk/clk-composite.c
> > index f30fb4b..5240e24 100644
> > --- a/drivers/clk/clk-composite.c
> > +++ b/drivers/clk/clk-composite.c
> > @@ -129,20 +129,13 @@ struct clk *clk_register_composite(struct device
> > *dev, const char *name,>
> > pr_err("%s: could not allocate composite clk\n",
> > __func__);
> > return ERR_PTR(-ENOMEM);
> >
> > }
> >
> > + clk_composite_ops = &composite->ops;
> >
> > init.name = name;
> > init.flags = flags | CLK_IS_BASIC;
> > init.parent_names = parent_names;
> > init.num_parents = num_parents;
> >
> > - /* allocate the clock ops */
> > - clk_composite_ops = kzalloc(sizeof(*clk_composite_ops),
> > GFP_KERNEL); - if (!clk_composite_ops) {
> > - pr_err("%s: could not allocate clk ops\n", __func__);
> > - kfree(composite);
> > - return ERR_PTR(-ENOMEM);
> > - }
> > -
> >
> > if (mux_hw && mux_ops) {
> >
> > if (!mux_ops->get_parent || !mux_ops->set_parent) {
> >
> > clk = ERR_PTR(-EINVAL);
> >
> > @@ -202,7 +195,6 @@ struct clk *clk_register_composite(struct device
> > *dev, const char *name,>
> > return clk;
> >
> > err:
> > - kfree(clk_composite_ops);
> >
> > kfree(composite);
> > return clk;
> >
> > }
> >
> > diff --git a/include/linux/clk-provider.h
> > b/include/linux/clk-provider.h index f0ac818..bb5d36a 100644
> > --- a/include/linux/clk-provider.h
> > +++ b/include/linux/clk-provider.h
> > @@ -346,6 +346,8 @@ struct clk_composite {
> >
> > const struct clk_ops *mux_ops;
> > const struct clk_ops *div_ops;
> > const struct clk_ops *gate_ops;
> >
> > +
> > + const struct clk_ops ops;
> >
> > };
> >
> > struct clk *clk_register_composite(struct device *dev, const char
> > *name,
> This will work, but there is no harm in allocating dynamically. What is
> preferred?

IMHO it is always better to allocate one bigger structure than several
smaller if they are always needed together and one cannot exist without
others.

Best regards,
--
Tomasz Figa
Samsung Poland R&D Center
SW Solution Development, Linux Platform