Re: [U-Boot] [PATCH] bugfix i.mx6 pwm: prevent overflow of period_c * duty_ns

On 06/05/2015 09:57, Brecht Neyrinck wrote:

Prevent overflow by casting duty_ns to ull first. This bug came up when trying to create a 200 Hz PWM

Signed-off-by: Brecht Neyrinck bnrn@psicontrol.com

drivers/pwm/pwm-imx-util.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pwm/pwm-imx-util.c b/drivers/pwm/pwm-imx-util.c index f1d0b35..79d86028 100644 --- a/drivers/pwm/pwm-imx-util.c +++ b/drivers/pwm/pwm-imx-util.c @@ -56,7 +56,7 @@ int pwm_imx_get_parms(int period_ns, int duty_ns, unsigned long *period_c, *prescale = *period_c / 0x10000 + 1;

*period_c /= *prescale;

• c = (unsigned long long)(*period_c * duty_ns);

• c = *period_c * (unsigned long long)duty_ns; do_div(c, period_ns); *duty_c = c;

Applied to u-boot-imx, thanks !

Best regards, Stefano Babic