[PATCH] clk: mux: let clk_mux_val_to_index return U8_MAX in the error case

Heiner Kallweit
2023-04-12T06:19:32Z

Currently this function may return a negative errno, but almost no
user checks for the error case. Only imx_clk_gpr_mux_get_parent()
does, but mentions in a comment that they'd prefer a dummy value.
Other users cast the negative errno to u8 instead, what may result
in unwanted results.
Let's deal with this by returning u8 and U8_MAX in the error case.
Then clk_core_get_parent_by_index() can detect that the index is
out of range.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.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 fa817c317..be0f317ee 100644
--- a/drivers/clk/clk-mux.c
+++ b/drivers/clk/clk-mux.c
@@ -40,8 +40,8 @@ static inline void clk_mux_writel(struct clk_mux *mux, u32 val)
writel(val, mux->reg);
}

-int clk_mux_val_to_index(struct clk_hw *hw, const u32 *table, unsigned int flags,
- unsigned int val)
+u8 clk_mux_val_to_index(struct clk_hw *hw, const u32 *table, unsigned int flags,
+ unsigned int val)
{
int num_parents = clk_hw_get_num_parents(hw);

@@ -51,7 +51,7 @@ int clk_mux_val_to_index(struct clk_hw *hw, const u32 *table, unsigned int flags
for (i = 0; i < num_parents; i++)
if (table[i] == val)
return i;
- return -EINVAL;
+ return U8_MAX;
}

if (val && (flags & CLK_MUX_INDEX_BIT))
@@ -61,7 +61,7 @@ int clk_mux_val_to_index(struct clk_hw *hw, const u32 *table, unsigned int flags
val--;

if (val >= num_parents)
- return -EINVAL;
+ return U8_MAX;

return val;
}
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index faad3cdc1..62fb4118c 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -1069,8 +1069,8 @@ struct clk *clk_register_mux_table(struct device *dev, const char *name,
NULL, (parent_data), (flags), (reg), (shift), \
BIT((width)) - 1, (clk_mux_flags), table, (lock))

-int clk_mux_val_to_index(struct clk_hw *hw, const u32 *table, unsigned int flags,
- unsigned int val);
+u8 clk_mux_val_to_index(struct clk_hw *hw, const u32 *table, unsigned int flags,
+ unsigned int val);
unsigned int clk_mux_index_to_val(const u32 *table, unsigned int flags, u8 index);

void clk_unregister_mux(struct clk *clk);
--
2.40.0