Hello Uwe,
Thanks for the explain, now i can understand it better.
So, if redefining period and duty as u64 in gb_pwm_config_request is an
acceptable solution, i will send patch v2.
BR
Song
在 2022/2/11 15:16, Uwe Kleine-König 写道:
Hello ,
On Fri, Feb 11, 2022 at 11:06:33AM +0800, Song Chen wrote:
在 2022/2/10 18:03, Uwe Kleine-König 写道:
On Thu, Feb 10, 2022 at 05:05:02PM +0800, Song Chen wrote:
Introduce apply in pwm_ops to replace legacy operations,
like enable, disable, config and set_polarity.
Signed-off-by: Song Chen <chensong_2000@xxxxxx>
---
drivers/staging/greybus/pwm.c | 46 +++++++++++++++--------------------
1 file changed, 19 insertions(+), 27 deletions(-)
diff --git a/drivers/staging/greybus/pwm.c b/drivers/staging/greybus/pwm.c
index 891a6a672378..e1889cf979b2 100644
--- a/drivers/staging/greybus/pwm.c
+++ b/drivers/staging/greybus/pwm.c
@@ -204,43 +204,35 @@ static void gb_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
gb_pwm_deactivate_operation(pwmc, pwm->hwpwm);
}
-static int gb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
- int duty_ns, int period_ns)
-{
- struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
-
- return gb_pwm_config_operation(pwmc, pwm->hwpwm, duty_ns, period_ns);
-};
-
-static int gb_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
- enum pwm_polarity polarity)
+static int gb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ const struct pwm_state *state)
{
+ int ret;
struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
- return gb_pwm_set_polarity_operation(pwmc, pwm->hwpwm, polarity);
-};
-
-static int gb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
- struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
+ /* set period and duty cycle*/
+ ret = gb_pwm_config_operation(pwmc, pwm->hwpwm, state->duty_cycle, state->period);
gb_pwm_config_operation's 3rd parameter is an u32, so you're loosing
bits here as state->duty_cycle is a u64. Ditto for period.
originally, pwm_apply_state --> pwm_apply_legacy --> gb_pwm_config -->
gb_pwm_config_operation is also loosing bits, does it mean greybus can live
with that?
This is true, I tried to address that, but Thierry had concerns.
(https://lore.kernel.org/all/20210312212119.1342666-1-u.kleine-koenig@xxxxxxxxxxxxxx/
was the patch I suggested.)
Or redefine gb_pwm_config_request, switch duty and period to __le64?
Don't use __le64, this is only for representing (little endian) register
values. u64 would be the right one.
Also it would be nice if you go from
.duty_cycle = A, .period = B, .enabled = 1
to
.duty_cycle = C, .period = D, .enabled = 0
that C/D wasn't visible on the output pin. So please disable earlier
(but keep enable at the end).
sorry, i don't quite understand this part,
To reexplain: If your hardware is configured for
.duty_cycle = A, .period = B, .enabled = 1
and pwm_apply is called with
.duty_cycle = C, .period = D, .enabled = 0
you configured the registers for .duty_cycle and .period first and only
then disable the PWM. This usually results in glitches because the
hardware shortly runs with
.duty_cycle = C, .period = D, .enabled = 1
. So the idea is, to disable before configuring duty and period if the
eventual goal is a disabled state.
understood, thanks.
but is below code looking good to
you?
static int gb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
int err;
bool enabled = pwm->state.enabled;
struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
/* set polarity */
if (state->polarity != pwm->state.polarity) {
if (enabled) {
gb_pwm_disable_operation(pwmc, pwm->hwpwm);
enabled = false;
}
err = gb_pwm_set_polarity_operation(pwmc, pwm->hwpwm, state->polarity);
if (err)
return err;
}
if (!state->enabled) {
if (enabled)
gb_pwm_disable_operation(pwmc, pwm->hwpwm);
return 0;
}
/* set period and duty cycle*/
err = gb_pwm_config_operation(pwmc, pwm->hwpwm, state->duty_cycle, state->period);
if (err)
return err;
/* enable/disable */
if (!enabled)
return gb_pwm_enable_operation(pwmc, pwm->hwpwm);
return 0;
}
This looks good.
Best regards
Uwe
