[PATCH 4.0 04/22] clk: at91: pll: fix input range validity check

Greg Kroah-Hartman
2015-06-27T01:16:08Z

From: Boris Brezillon <boris.brezillon@free-electrons.com>

commit 6c7b03e1aef2e92176435f4fa562cc483422d20f upstream.

The PLL impose a certain input range to work correctly, but it appears that
this input range does not apply on the input clock (or parent clock) but
on the input clock after it has passed the PLL divisor.
Fix the implementation accordingly.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reported-by: Jonas Andersson <jonas@microbit.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/clk/at91/clk-pll.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

--- a/drivers/clk/at91/clk-pll.c
+++ b/drivers/clk/at91/clk-pll.c
@@ -173,8 +173,7 @@ static long clk_pll_get_best_div_mul(str
int i = 0;

/* Check if parent_rate is a valid input rate */
- if (parent_rate < characteristics->input.min ||
- parent_rate > characteristics->input.max)
+ if (parent_rate < characteristics->input.min)
return -ERANGE;

/*
@@ -187,6 +186,15 @@ static long clk_pll_get_best_div_mul(str
if (!mindiv)
mindiv = 1;

+ if (parent_rate > characteristics->input.max) {
+ tmpdiv = DIV_ROUND_UP(parent_rate, characteristics->input.max);
+ if (tmpdiv > PLL_DIV_MAX)
+ return -ERANGE;
+
+ if (tmpdiv > mindiv)
+ mindiv = tmpdiv;
+ }
+
/*
* Calculate the maximum divider which is limited by PLL register
* layout (limited by the MUL or DIV field size).