[PATCH] clk: fix clk_mux_val_to_index() error value

[PATCH] clk: fix clk_mux_val_to_index() error value

[Jerome Brunet]

clk_mux_val_to_index() is meant to be used by .get_parent(), which
returns a u8, so when the value provided does not map to any valid index,
it is not a good idea to return a negative error value.

Instead, return num_parents which we know is an invalid index and let
CCF deal with it.

Fixes: 77deb66d262f ("clk: mux: add helper function for index/value translation")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
 drivers/clk/clk-mux.c        | 8 ++++----
 include/linux/clk-provider.h | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c
index 1628b93655ed..b64e475802cc 100644
--- a/drivers/clk/clk-mux.c
+++ b/drivers/clk/clk-mux.c
@@ -26,8 +26,8 @@
  * parent - parent is adjustable through clk_set_parent
  */
 
-int clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int flags,
-			 unsigned int val)
+u8 clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int flags,
+			unsigned int val)
 {
 	int num_parents = clk_hw_get_num_parents(hw);
 
@@ -37,7 +37,7 @@ int clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int flags,
 		for (i = 0; i < num_parents; i++)
 			if (table[i] == val)
 				return i;
-		return -EINVAL;
+		return num_parents;
 	}
 
 	if (val && (flags & CLK_MUX_INDEX_BIT))
@@ -47,7 +47,7 @@ int clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int flags,
 		val--;
 
 	if (val >= num_parents)
-		return -EINVAL;
+		return num_parents;
 
 	return val;
 }
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 60c51871b04b..fc20886ef069 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -550,8 +550,8 @@ struct clk_hw *clk_hw_register_mux_table(struct device *dev, const char *name,
 		void __iomem *reg, u8 shift, u32 mask,
 		u8 clk_mux_flags, u32 *table, spinlock_t *lock);
 
-int clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int flags,
-			 unsigned int val);
+u8 clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int flags,
+			unsigned int val);
 unsigned int clk_mux_index_to_val(u32 *table, unsigned int flags, u8 index);
 
 void clk_unregister_mux(struct clk *clk);
-- 
2.19.1

Re: [PATCH] clk: fix clk_mux_val_to_index() error value

[Stephen Boyd]

Quoting Jerome Brunet (2018-12-04 08:34:03)
> clk_mux_val_to_index() is meant to be used by .get_parent(), which
> returns a u8, so when the value provided does not map to any valid index,
> it is not a good idea to return a negative error value.
> 
> Instead, return num_parents which we know is an invalid index and let
> CCF deal with it.
> 
> Fixes: 77deb66d262f ("clk: mux: add helper function for index/value translation")
> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
> ---

Thanks!

> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 60c51871b04b..fc20886ef069 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -550,8 +550,8 @@ struct clk_hw *clk_hw_register_mux_table(struct device *dev, const char *name,
>                 void __iomem *reg, u8 shift, u32 mask,
>                 u8 clk_mux_flags, u32 *table, spinlock_t *lock);
>  
> -int clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int flags,
> -                        unsigned int val);
> +u8 clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int flags,

I wonder if we should just make this unsigned int? Does it hurt at all
to have it be a wider type even though it doesn't match the CCF decision
to make this a u8 for the parent index number space?

Re: [PATCH] clk: fix clk_mux_val_to_index() error value

[Jerome Brunet]

On Tue, 2018-12-04 at 10:43 -0800, Stephen Boyd wrote:
> Quoting Jerome Brunet (2018-12-04 08:34:03)
> > clk_mux_val_to_index() is meant to be used by .get_parent(), which
> > returns a u8, so when the value provided does not map to any valid index,
> > it is not a good idea to return a negative error value.
> > 
> > Instead, return num_parents which we know is an invalid index and let
> > CCF deal with it.
> > 
> > Fixes: 77deb66d262f ("clk: mux: add helper function for index/value
> > translation")
> > Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
> > ---
> 
> Thanks!
> 
> > diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> > index 60c51871b04b..fc20886ef069 100644
> > --- a/include/linux/clk-provider.h
> > +++ b/include/linux/clk-provider.h
> > @@ -550,8 +550,8 @@ struct clk_hw *clk_hw_register_mux_table(struct device
> > *dev, const char *name,
> >                 void __iomem *reg, u8 shift, u32 mask,
> >                 u8 clk_mux_flags, u32 *table, spinlock_t *lock);
> >  
> > -int clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int
> > flags,
> > -                        unsigned int val);
> > +u8 clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int
> > flags,
> 
> I wonder if we should just make this unsigned int? Does it hurt at all
> to have it be a wider type even though it doesn't match the CCF decision
> to make this a u8 for the parent index number space?
> 

I also wondered about this but since the target is get_parent(), I just
aligned the two.

In the end, I don't really care, as you prefer. Just let me know if you would
like a v2 with this change

Re: [PATCH] clk: fix clk_mux_val_to_index() error value

[Stephen Boyd]

Quoting Jerome Brunet (2018-12-04 11:55:10)
> On Tue, 2018-12-04 at 10:43 -0800, Stephen Boyd wrote:
> > Quoting Jerome Brunet (2018-12-04 08:34:03)
> > > clk_mux_val_to_index() is meant to be used by .get_parent(), which
> > > returns a u8, so when the value provided does not map to any valid index,
> > > it is not a good idea to return a negative error value.
> > > 
> > > Instead, return num_parents which we know is an invalid index and let
> > > CCF deal with it.
> > > 
> > > Fixes: 77deb66d262f ("clk: mux: add helper function for index/value
> > > translation")
> > > Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
> > > ---
> > 
> > Thanks!
> > 
> > > diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> > > index 60c51871b04b..fc20886ef069 100644
> > > --- a/include/linux/clk-provider.h
> > > +++ b/include/linux/clk-provider.h
> > > @@ -550,8 +550,8 @@ struct clk_hw *clk_hw_register_mux_table(struct device
> > > *dev, const char *name,
> > >                 void __iomem *reg, u8 shift, u32 mask,
> > >                 u8 clk_mux_flags, u32 *table, spinlock_t *lock);
> > >  
> > > -int clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int
> > > flags,
> > > -                        unsigned int val);
> > > +u8 clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int
> > > flags,
> > 
> > I wonder if we should just make this unsigned int? Does it hurt at all
> > to have it be a wider type even though it doesn't match the CCF decision
> > to make this a u8 for the parent index number space?
> > 
> 
> I also wondered about this but since the target is get_parent(), I just
> aligned the two.
> 
> In the end, I don't really care, as you prefer. Just let me know if you would
> like a v2 with this change
> 

Ok I may just make it unsigned int when applying then.