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| author |   Jitao Shi <jitao.shi@mediatek.com> | 2021-08-08 21:24:32 +0800 |
|---|---|---|
| committer |   Thierry Reding <thierry.reding@gmail.com> | 2021-09-02 22:27:44 +0200 |
| commit | 331e049dec64c2d269648a3ea4ea6aae8a54b4ac (patch) | |
| tree | ba043dde61cc93e9de83767f64334d26fcae5d2b /drivers/pwm | |
| parent | pwm: mtk-disp: Implement atomic API .apply() (diff) | |
| download | linux-dev-331e049dec64c2d269648a3ea4ea6aae8a54b4ac.tar.xz linux-dev-331e049dec64c2d269648a3ea4ea6aae8a54b4ac.zip | |
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>
Diffstat (limited to 'drivers/pwm')
| -rw-r--r-- | drivers/pwm/pwm-mtk-disp.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/pwm/pwm-mtk-disp.c b/drivers/pwm/pwm-mtk-disp.c index caabcb30f90e..73f8103a782c 100644 --- a/drivers/pwm/pwm-mtk-disp.c +++ b/drivers/pwm/pwm-mtk-disp.c @@ -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, |