[PATCH 5.10 688/717] clk: ingenic: Fix divider calculation with div tables

Greg Kroah-Hartman
2020-12-28T14:38:25Z

From: Paul Cercueil <paul@crapouillou.net>

commit 11a163f2c7d6a9f27ce144cd7e367a81c851621a upstream.

The previous code assumed that a higher hardware value always resulted
in a bigger divider, which is correct for the regular clocks, but is
an invalid assumption when a divider table is provided for the clock.

Perfect example of this is the PLL0_HALF clock, which applies a /2
divider with the hardware value 0, and a /1 divider otherwise.

Fixes: a9fa2893fcc6 ("clk: ingenic: Add support for divider tables")
Cc: <stable@vger.kernel.org> # 5.2
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20201212135733.38050-1-paul@crapouillou.net
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/clk/ingenic/cgu.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

--- a/drivers/clk/ingenic/cgu.c
+++ b/drivers/clk/ingenic/cgu.c
@@ -392,15 +392,21 @@ static unsigned int
ingenic_clk_calc_hw_div(const struct ingenic_cgu_clk_info *clk_info,
unsigned int div)
{
- unsigned int i;
+ unsigned int i, best_i = 0, best = (unsigned int)-1;

for (i = 0; i < (1 << clk_info->div.bits)
&& clk_info->div.div_table[i]; i++) {
- if (clk_info->div.div_table[i] >= div)
- return i;
+ if (clk_info->div.div_table[i] >= div &&
+ clk_info->div.div_table[i] < best) {
+ best = clk_info->div.div_table[i];
+ best_i = i;
+
+ if (div == best)
+ break;
+ }
}

- return i - 1;
+ return best_i;
}

static unsigned