From: Ian Abbott <abbotti@xxxxxxxxx> commit 8e2a589a3fc36ce858d42e767c3bcd8fc62a512b upstream. `dt3k_ns_to_timer()` determines the prescaler and divisor to use to produce a desired timing period. It is influenced by a rounding mode and can round the divisor up, down, or to the nearest value. However, the code for rounding up currently does the same as rounding down! Fix ir by using the `DIV_ROUND_UP()` macro to calculate the divisor when rounding up. Also, change the types of the `divider`, `base` and `prescale` variables from `int` to `unsigned int` to avoid mixing signed and unsigned types in the calculations. Also fix a typo in a nearby comment: "improvment" => "improvement". Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx> Cc: stable <stable@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20190812120814.21188-1-abbotti@xxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/staging/comedi/drivers/dt3000.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/staging/comedi/drivers/dt3000.c +++ b/drivers/staging/comedi/drivers/dt3000.c @@ -342,9 +342,9 @@ static irqreturn_t dt3k_interrupt(int ir static int dt3k_ns_to_timer(unsigned int timer_base, unsigned int *nanosec, unsigned int flags) { - int divider, base, prescale; + unsigned int divider, base, prescale; - /* This function needs improvment */ + /* This function needs improvement */ /* Don't know if divider==0 works. */ for (prescale = 0; prescale < 16; prescale++) { @@ -358,7 +358,7 @@ static int dt3k_ns_to_timer(unsigned int divider = (*nanosec) / base; break; case CMDF_ROUND_UP: - divider = (*nanosec) / base; + divider = DIV_ROUND_UP(*nanosec, base); break; } if (divider < 65536) {
