hollalinux
/
linux-sg2042
mirror of https://github.com/sophgo/linux-riscv.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

pwm: mtk-disp: Fix overflow in period and duty calculation 

Current calculation for period and high_width may have 64-bit overflow.
state->period and rate are u64. rate * state->period will overflow.

clk_div = div_u64(rate * state->period, NSEC_PER_SEC)
period = div64_u64(rate * state->period, div);
high_width = div64_u64(rate * state->duty_cycle, div);

This patch is to resolve it by using mul_u64_u64_div_u64().

Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Jitao Shi 2021-08-08 21:24:32 +08:00 committed by Thierry Reding
parent 888a623db5
commit 331e049dec
1 changed files with 3 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/pwm/pwm-mtk-disp.c
View File

@ -119,7 +119,7 @@ static int mtk_disp_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
* high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1))
*/
rate = clk_get_rate(mdp->clk_main);
clk_div = div_u64(rate * state->period, NSEC_PER_SEC) >>
clk_div = mul_u64_u64_div_u64(state->period, rate, NSEC_PER_SEC) >>
PWM_PERIOD_BIT_WIDTH;
if (clk_div > PWM_CLKDIV_MAX) {
if (!mdp->enabled) {
@ -130,11 +130,11 @@ static int mtk_disp_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
}
div = NSEC_PER_SEC * (clk_div + 1);
period = div64_u64(rate * state->period, div);
period = mul_u64_u64_div_u64(state->period, rate, div);
if (period > 0)
period--;
high_width = div64_u64(rate * state->duty_cycle, div);
high_width = mul_u64_u64_div_u64(state->duty_cycle, rate, div);
value = period | (high_width << PWM_HIGH_WIDTH_SHIFT);
mtk_disp_pwm_update_bits(mdp, mdp->data->con0,