From: Hyong Bin Kim <hyongbink@xxxxxxxxxx>
duty_ns * (1 << PWM_DUTY_WIDTH) could overflow in integer calcualtion
when PWM rate is low. Hence do all calculation on unsigned long long
to avoid overflow.
Signed-off-by: Hyong Bin Kim <hyongbink@xxxxxxxxxx>
Signed-off-by: Laxman Dewangan <ldewangan@xxxxxxxxxx>
---
drivers/pwm/pwm-tegra.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
index 575ca8e..49cefd5 100644
--- a/drivers/pwm/pwm-tegra.c
+++ b/drivers/pwm/pwm-tegra.c
@@ -69,7 +69,7 @@ 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;
+ unsigned long long c = duty_ns;
unsigned long rate, hz;
u32 val = 0;
int err;
@@ -79,7 +79,8 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
* per (1 << PWM_DUTY_WIDTH) cycles and make sure to round to the
* nearest integer during division.
*/
- c = duty_ns * (1 << PWM_DUTY_WIDTH) + period_ns / 2;
+ c *= (1 << PWM_DUTY_WIDTH);
+ c += period_ns / 2;
do_div(c, period_ns);
val = (u32)c << PWM_DUTY_SHIFT;
--
2.1.4
--
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