ARM: tegra: fix U16 divider range check

A U16 divider can divide a clock by 1..64K. However, the range-check
in clk_div16_get_divider() limited the range to 1..256. Fix this. NVIDIA's
downstream kernels already have the fixed range-check.

In practice this is a problem on Whistler's I2C bus, which uses a bus
clock rate of 100KHz (rather than the more common 400KHz on Tegra boards),
which requires a HW module clock of 8*100KHz. The parent clock is 216MHz,
leading to a desired divider of 270. Prior to conversion to the common
clock framework, this range error was somehow ignored/irrelevant and
caused no problems. However, the common clock framework evidently has
more rigorous error-checking, so this failure causes the I2C bus to fail
to operate correctly.

Signed-off-by: Stephen Warren <swarren@nvidia.com>

diff --git a/arch/arm/mach-tegra/tegra2_clocks.c b/arch/arm/mach-tegra/tegra2_clocks.c
index a703844..83ccb85 100644 (file)
--- a/arch/arm/mach-tegra/tegra2_clocks.c
+++ b/arch/arm/mach-tegra/tegra2_clocks.c
@@ -223,7 +223,7 @@ static int clk_div16_get_divider(unsigned long parent_rate, unsigned long rate)
        if (divider_u16 - 1 < 0)
                return 0;
 
-       if (divider_u16 - 1 > 255)
+       if (divider_u16 - 1 > 0xFFFF)
                return -EINVAL;
 
        return divider_u16 - 1;