On Tue, Jan 21, 2025 at 04:47:46PM +0800, Nylon Chen wrote:
> Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxx> 於 2025年1月21日 週二 下午3:47寫道：
> >
> > Hello,
> >
> > On Sun, Jan 19, 2025 at 03:03:16PM +0800, Nylon Chen wrote:
> > > I ran some basic tests by changing the period and duty cycle in both
> > > decreasing and increasing sequences (see the script below).
> >
> > What is clk_get_rate(ddata->clk) for you?
> 130 MHz
OK, so the possible period lengths are
(1 << (16 + scale)) / (130 MHz)
for scale in [0, .. 15], right? That's
2^scale * 504123.07692307694 ns
So testing period in the range between 5000 ns and 15000 ns isn't
sensible? Did I get something wrong? If the above is right, switching
between period=1008246 ns and 1008247 ns is likely to trigger a
warning.
Maybe also something like
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 7e863c2cd44b..6c82aca84472 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -2247,9 +2247,10 @@ static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
for (i = 0; i < chip->npwm; i++) {
struct pwm_device *pwm = &chip->pwms[i];
- struct pwm_state state;
+ struct pwm_state state, hwstate;
pwm_get_state(pwm, &state);
+ pwm_get_state_hw(pwm, &hwstate);
seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label);
@@ -2259,8 +2260,8 @@ static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
if (state.enabled)
seq_puts(s, " enabled");
- seq_printf(s, " period: %llu ns", state.period);
- seq_printf(s, " duty: %llu ns", state.duty_cycle);
+ seq_printf(s, " period: %llu (%llu) ns", state.period, hwstate.period);
+ seq_printf(s, " duty: %llu (%llu) ns", state.duty_cycle, hwstate.duty_cycle);
seq_printf(s, " polarity: %s",
state.polarity ? "inverse" : "normal");
is useful for debugging to see what is actually implemented for a given
request.
Having said that, I don't like struct pwm_sifive_ddata::real_period and
pwm_sifive_ddata::approx_period. These complicate the calculation and
.get_state should better calculate the period instead of just sticking
to ddata->real_period.
Best regards
Uwe
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