mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-02 15:18:19 +00:00
backlight: pwm_bl: Fix overflow condition
[ Upstream commit 5d0c49aceb
]
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 <dbasehore@chromium.org>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
23b22186b2
commit
b04c22da18
1 changed files with 5 additions and 2 deletions
|
@ -79,14 +79,17 @@ 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)
|
||||
|
|
Loading…
Reference in a new issue