Re: [PATCH 01/16] clk: permit to define a custom parent for clk_hw_get_parent_index

Ansuel Smith
2022-03-15T18:07:32Z

On Tue, Mar 15, 2022 at 10:55:18AM -0700, Stephen Boyd wrote:
> Quoting Ansuel Smith (2022-03-13 12:04:04)
> > Clk can have multiple parents. Some clk may require to get the cached
> > index of other parent that are not current associated with the clk.
> > Extend clk_hw_get_parent_index() with an optional parent to permit a
> > driver to get the cached index. If parent is NULL, the parent associated
> > with the provided hw clk is used.
> >
> > Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
> > ---
> > drivers/clk/clk.c | 14 +++++++++-----
> > drivers/clk/tegra/clk-periph.c | 2 +-
> > drivers/clk/tegra/clk-sdmmc-mux.c | 2 +-
> > drivers/clk/tegra/clk-super.c | 4 ++--
> > include/linux/clk-provider.h | 2 +-
> > 5 files changed, 14 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> > index 8de6a22498e7..fe42f56bfbdf 100644
> > --- a/drivers/clk/clk.c
> > +++ b/drivers/clk/clk.c
> > @@ -1711,15 +1711,19 @@ static int clk_fetch_parent_index(struct clk_core *core,
> > /**
> > * clk_hw_get_parent_index - return the index of the parent clock
> > * @hw: clk_hw associated with the clk being consumed
> > + * @parent: optional clk_hw of the parent to be fetched
> > *
> > - * Fetches and returns the index of parent clock. Returns -EINVAL if the given
> > - * clock does not have a current parent.
> > + * Fetches and returns the index of parent clock. If parent is not
> > + * provided the parent of hw is used.
> > + * Returns -EINVAL if the given clock does not have a current parent.
> > */
> > -int clk_hw_get_parent_index(struct clk_hw *hw)
> > +int clk_hw_get_parent_index(struct clk_hw *hw, struct clk_hw *parent)
>
> Please introduce another API vs. tacking on an "output" argument to this
> API. That makes the patch less invasive. And it can also return a
> pointer instead of an integer in that case.
>

Any suggestion about the name? clk_hw_fetch_parent_index? That would be
a direct access of the internal clk_fetch_parent_index.

The name is already not that intuitive as is. The alternative is to make
it extra long, don't know if that's a problem...
Something like clk_hw_get_parent_index_by_parent? (that is even more
confusing)

> > {
> > - struct clk_hw *parent = clk_hw_get_parent(hw);
> > + /* With parent NULL get the current parent of hw */
> > + if (!parent)
> > + parent = clk_hw_get_parent(hw);

--
Ansuel