On Tue, Aug 29, 2017 at 01:34:34PM -0700, Derek Basehore wrote: > This fixes an overflow condition that can happen with high max > brightness and period values in compute_duty_cycle. This fixes it by > using a 64 bit variable for computing the duty cycle. > > Signed-off-by: Derek Basehore <[email protected]> > ---
I believe this is the correct v2 patch, and I agree that Derek is confused by his mail client :) Reviewed-by: Brian Norris <[email protected]> > drivers/video/backlight/pwm_bl.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/video/backlight/pwm_bl.c > b/drivers/video/backlight/pwm_bl.c > index 76311ec5e400..5ccc8e34b7a6 100644 > --- a/drivers/video/backlight/pwm_bl.c > +++ b/drivers/video/backlight/pwm_bl.c > @@ -88,14 +88,17 @@ static void pwm_backlight_power_off(struct pwm_bl_data > *pb) > static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness) > { > unsigned int lth = pb->lth_brightness; > - int duty_cycle; > + u64 duty_cycle; > > if (pb->levels) > duty_cycle = pb->levels[brightness]; > else > duty_cycle = brightness; > > - return (duty_cycle * (pb->period - lth) / pb->scale) + lth; > + duty_cycle *= pb->period - lth; > + do_div(duty_cycle, pb->scale); > + > + return duty_cycle + lth; > } > > static int pwm_backlight_update_status(struct backlight_device *bl) > -- > 2.14.1.342.g6490525c54-goog >
