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pwm: axi-pwmgen: Let .round_waveform_tohw() signal when request was rounded up

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The .round_waveform_tohw() is supposed to return 1 if the requested
waveform cannot be implemented by rounding down all parameters. Also
adapt the corresponding comment to better describe why the implemented
procedure is right.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Tested-by: Trevor Gamblin <tgamblin@baylibre.com>
Link: https://lore.kernel.org/r/ba451573f0218d76645f068cec78bd97802cf010.1743844730.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
This commit is contained in:
Uwe Kleine-König 2025-04-05 11:27:16 +02:00 • committed by Uwe Kleine-König
parent fda6e0034e
commit a85e08a05b
1 changed files with 7 additions and 3 deletions
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10
drivers/pwm/pwm-axi-pwmgen.c
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@ -75,6 +75,7 @@ static int axi_pwmgen_round_waveform_tohw(struct pwm_chip *chip,
{
struct axi_pwmgen_waveform *wfhw = _wfhw;
struct axi_pwmgen_ddata *ddata = axi_pwmgen_ddata_from_chip(chip);
int ret = 0;
if (wf->period_length_ns == 0) {
*wfhw = (struct axi_pwmgen_waveform){
@ -91,12 +92,15 @@ static int axi_pwmgen_round_waveform_tohw(struct pwm_chip *chip,
if (wfhw->period_cnt == 0) {
/*
* The specified period is too short for the hardware.
* Let's round .duty_cycle down to 0 to get a (somewhat)
* valid result.
* So round up .period_cnt to 1 (i.e. the smallest
* possible period). With .duty_cycle and .duty_offset
* being less than or equal to .period, their rounded
* value must be 0.
*/
wfhw->period_cnt = 1;
wfhw->duty_cycle_cnt = 0;
wfhw->duty_offset_cnt = 0;
ret = 1;
} else {
wfhw->duty_cycle_cnt = min_t(u64,
mul_u64_u32_div(wf->duty_length_ns, ddata->clk_rate_hz, NSEC_PER_SEC),
@ -111,7 +115,7 @@ static int axi_pwmgen_round_waveform_tohw(struct pwm_chip *chip,
pwm->hwpwm, wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns,
ddata->clk_rate_hz, wfhw->period_cnt, wfhw->duty_cycle_cnt, wfhw->duty_offset_cnt);
return 0;
return ret;
}
static int axi_pwmgen_round_waveform_fromhw(struct pwm_chip *chip, struct pwm_device *pwm,