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pwm: rp1: Silently correct illegal values #7133

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Merged
merged 2 commits into from
Nov 13, 2025
+21 −10
Merged

pwm: rp1: Silently correct illegal values #7133

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e390613
pwm: rp1: Silently correct illegal values
pelwell Nov 11, 2025
bfbbca1
pwm: rp1: Correct period off-by-1 error
pelwell Nov 11, 2025
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31 changes: 21 additions & 10 deletions drivers/pwm/pwm-pio-rp1.c
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Original file line number Diff line number Diff line change
Expand Up @@ -83,7 +83,7 @@ static inline void pwm_program_init(PIO pio, uint sm, uint offset, uint pin)
/* Write `period` to the input shift register - must be disabled */
static void pio_pwm_set_period(PIO pio, uint sm, uint32_t period)
{
pio_sm_put_blocking(pio, sm, period);
pio_sm_put_blocking(pio, sm, period - 1);
pio_sm_exec(pio, sm, pio_encode_pull(false, false));
pio_sm_exec(pio, sm, pio_encode_out(pio_isr, 32));
}
Expand All @@ -101,15 +101,12 @@ static int pwm_pio_rp1_apply(struct pwm_chip *chip, struct pwm_device *pwm,
uint32_t new_duty_cycle;
uint32_t new_period;

if (state->duty_cycle && state->duty_cycle < pwm_pio_resolution)
return -EINVAL;

if (state->duty_cycle != state->period &&
(state->period - state->duty_cycle < pwm_pio_resolution))
return -EINVAL;

new_period = state->period / pwm_pio_resolution;
new_duty_cycle = state->duty_cycle / pwm_pio_resolution;
new_period = DIV_ROUND_CLOSEST(state->period, pwm_pio_resolution);
if (new_period < 2)
new_period = 2;
new_duty_cycle = DIV_ROUND_CLOSEST(state->duty_cycle, pwm_pio_resolution);
if (new_duty_cycle > new_period - 1)
new_duty_cycle = new_period - 1;

mutex_lock(&ppwm->mutex);

Expand Down Expand Up @@ -145,8 +142,22 @@ static int pwm_pio_rp1_apply(struct pwm_chip *chip, struct pwm_device *pwm,
return 0;
}

static int pwm_pio_rp1_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
struct pwm_pio_rp1 *ppwm = pwmchip_get_drvdata(chip);

state->enabled = ppwm->enabled;
state->polarity = ppwm->polarity;
state->period = ppwm->period * pwm_pio_resolution;
state->duty_cycle = ppwm->duty_cycle * pwm_pio_resolution;

return 0;
}

static const struct pwm_ops pwm_pio_rp1_ops = {
.apply = pwm_pio_rp1_apply,
.get_state = pwm_pio_rp1_get_state,
};

static int pwm_pio_rp1_probe(struct platform_device *pdev)
Expand Down