| Message ID | 20170412163320.11760-1-thierry.reding@gmail.com |
|---|---|
| State | Accepted |
| Headers | show |
On Wednesday 12 April 2017 10:03 PM, Thierry Reding wrote: > For very short periods, the result of the division might overflow the > unsigned long hz variable (on 32-bit architectures). Avoid that by > making it an unsigned long long. While at it, also remove an unneeded > local variable whose only purpose is to store a temporary computation. > > Signed-off-by: Thierry Reding <thierry.reding@gmail.com> > --- Acked-by: Laxman Dewangan <ldewangan@nvidia.com> -- To unsubscribe from this list: send the line "unsubscribe linux-pwm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c index 9c7f180b9f3a..c040f87ee144 100644 --- a/drivers/pwm/pwm-tegra.c +++ b/drivers/pwm/pwm-tegra.c @@ -75,9 +75,8 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, int duty_ns, int period_ns) { struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip); - unsigned long long c = duty_ns; - unsigned long rate, hz; - unsigned long long ns100 = NSEC_PER_SEC; + unsigned long long c = duty_ns, hz; + unsigned long rate; u32 val = 0; int err; @@ -98,9 +97,8 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, rate = clk_get_rate(pc->clk) >> PWM_DUTY_WIDTH; /* Consider precision in PWM_SCALE_WIDTH rate calculation */ - ns100 *= 100; - hz = DIV_ROUND_CLOSEST_ULL(ns100, period_ns); - rate = DIV_ROUND_CLOSEST(rate * 100, hz); + hz = DIV_ROUND_CLOSEST_ULL(100ULL * NSEC_PER_SEC, period_ns); + rate = DIV_ROUND_CLOSEST_ULL(100ULL * rate, hz); /* * Since the actual PWM divider is the register's frequency divider
For very short periods, the result of the division might overflow the unsigned long hz variable (on 32-bit architectures). Avoid that by making it an unsigned long long. While at it, also remove an unneeded local variable whose only purpose is to store a temporary computation. Signed-off-by: Thierry Reding <thierry.reding@gmail.com> --- drivers/pwm/pwm-tegra.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-)