diff options
| author | Uwe Kleine-König <u.kleine-koenig@baylibre.com> | 2025-08-11 18:01:02 +0200 |
|---|---|---|
| committer | Uwe Kleine-König <ukleinek@kernel.org> | 2025-09-15 11:39:43 +0200 |
| commit | 00f83f0e07e44e2f1fb94b223e77ab7b18ee2d7d (patch) | |
| tree | f19be721cccffc2aa15ba024d483d75b48ce997a | |
| parent | pwm: tiehrpwm: Fix various off-by-one errors in duty-cycle calculation (diff) | |
| download | linux-00f83f0e07e44e2f1fb94b223e77ab7b18ee2d7d.tar.gz linux-00f83f0e07e44e2f1fb94b223e77ab7b18ee2d7d.zip | |
pwm: tiehrpwm: Fix corner case in clock divisor calculation
The function set_prescale_div() is responsible for calculating the clock
divisor settings such that the input clock rate is divided down such that
the required period length is at most 0x10000 clock ticks. If period_cycles
is an integer multiple of 0x10000, the divisor period_cycles / 0x10000 is
good enough. So round up in the calculation of the required divisor and
compare it using >= instead of >.
Fixes: 19891b20e7c2 ("pwm: pwm-tiehrpwm: PWM driver support for EHRPWM")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/85488616d7bfcd9c32717651d0be7e330e761b9c.1754927682.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
| -rw-r--r-- | drivers/pwm/pwm-tiehrpwm.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/pwm/pwm-tiehrpwm.c b/drivers/pwm/pwm-tiehrpwm.c index a23e48b8523d..7a86cb090f76 100644 --- a/drivers/pwm/pwm-tiehrpwm.c +++ b/drivers/pwm/pwm-tiehrpwm.c @@ -161,7 +161,7 @@ static int set_prescale_div(unsigned long rqst_prescaler, u16 *prescale_div, *prescale_div = (1 << clkdiv) * (hspclkdiv ? (hspclkdiv * 2) : 1); - if (*prescale_div > rqst_prescaler) { + if (*prescale_div >= rqst_prescaler) { *tb_clk_div = (clkdiv << TBCTL_CLKDIV_SHIFT) | (hspclkdiv << TBCTL_HSPCLKDIV_SHIFT); return 0; @@ -224,7 +224,7 @@ static int ehrpwm_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, pc->period_cycles[pwm->hwpwm] = period_cycles; /* Configure clock prescaler to support Low frequency PWM wave */ - if (set_prescale_div(period_cycles/PERIOD_MAX, &ps_divval, + if (set_prescale_div(DIV_ROUND_UP(period_cycles, PERIOD_MAX), &ps_divval, &tb_divval)) { dev_err(pwmchip_parent(chip), "Unsupported values\n"); return -EINVAL; |