From 6bf6e04db5c7aa8f2e8b56ce6f2c1099f495270c Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Mon, 12 Aug 2019 13:08:14 +0100 Subject: [PATCH] staging: comedi: dt3000: Fix rounding up of timer divisor 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 Cc: stable Link: https://lore.kernel.org/r/20190812120814.21188-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/dt3000.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/staging/comedi/drivers/dt3000.c b/drivers/staging/comedi/drivers/dt3000.c index ce678837e5033..6404cd4687b9d 100644 --- a/drivers/staging/comedi/drivers/dt3000.c +++ b/drivers/staging/comedi/drivers/dt3000.c @@ -351,9 +351,9 @@ static irqreturn_t dt3k_interrupt(int irq, void *d) 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++) { @@ -367,7 +367,7 @@ static int dt3k_ns_to_timer(unsigned int timer_base, unsigned int *nanosec, divider = (*nanosec) / base; break; case CMDF_ROUND_UP: - divider = (*nanosec) / base; + divider = DIV_ROUND_UP(*nanosec, base); break; } if (divider < 65536) { -- 2.47.2