Re: [PATCH 4/4] pwm: pca9685: migrate config/enable/disable to apply

Uwe Kleine-König
2020-02-26T15:05:37Z

Hello,

On Wed, Feb 26, 2020 at 02:52:29PM +0100, Matthias Schiffer wrote:
> For consistency with disabled state, initialize all LEDs in FULL_OFF
> state during probe.
>
> This also fixes a broken interaction between config with 100% duty cycle
> (which would set the LED to FULL_ON) and enable (which would unset
> FULL_ON), effectively disabling the LED again when enable was called
> after config. This behaviour was observed with the leds-pwm driver when
> directly switching from 0 to maximum brightness.
>
> Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> ---
> drivers/pwm/pwm-pca9685.c | 53 +++++++++++----------------------------
> 1 file changed, 14 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
> index 370691b21107..e266cbbd39bf 100644
> --- a/drivers/pwm/pwm-pca9685.c
> +++ b/drivers/pwm/pwm-pca9685.c
> @@ -219,15 +219,16 @@ static void pca9685_set_sleep_mode(struct pca9685 *pca, bool enable)
> }
> }
>
> -static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> - int duty_ns, int period_ns)
> +static int pca9685_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> + const struct pwm_state *state)
> {
> struct pca9685 *pca = to_pca(chip);
> unsigned long long duty;
> int prescale;
>
> - if (period_ns != pca->period_ns) {
> - prescale = DIV_ROUND_CLOSEST(PCA9685_OSC_CLOCK_MHZ * period_ns,
> + if (state->period != pca->period_ns) {
> + prescale = DIV_ROUND_CLOSEST(PCA9685_OSC_CLOCK_MHZ *
> + state->period,
> PCA9685_COUNTER_RANGE * 1000) - 1;
>
> if (prescale >= PCA9685_PRESCALE_MIN &&
> @@ -247,7 +248,7 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> /* Wake the chip up */
> pca9685_set_sleep_mode(pca, false);
>
> - pca->period_ns = period_ns;
> + pca->period_ns = state->period;
> } else {
> dev_err(chip->dev,
> "prescaler not set: period out of bounds!\n");
> @@ -255,13 +256,13 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> }
> }
>
> - if (duty_ns < 1) {
> + if (!state->enabled || state->duty_cycle < 1) {
> + /* Set the full OFF bit */
> regmap_write(pca->regmap, LED_N_OFF_H(pwm->hwpwm), LED_FULL);
> -
> return 0;
> }
>
> - if (duty_ns == period_ns) {
> + if (state->duty_cycle == state->period) {
> /* Clear both OFF registers */
> regmap_write(pca->regmap, LED_N_OFF_L(pwm->hwpwm), 0x0);
> regmap_write(pca->regmap, LED_N_OFF_H(pwm->hwpwm), 0x0);
> @@ -272,8 +273,8 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> return 0;
> }
>
> - duty = PCA9685_COUNTER_RANGE * (unsigned long long)duty_ns;
> - duty = DIV_ROUND_UP_ULL(duty, period_ns);
> + duty = PCA9685_COUNTER_RANGE * (unsigned long long)state->duty_cycle;
> + duty = DIV_ROUND_UP_ULL(duty, state->period);
>
> regmap_write(pca->regmap, LED_N_OFF_L(pwm->hwpwm), (int)duty & 0xff);
> regmap_write(pca->regmap, LED_N_OFF_H(pwm->hwpwm),
> @@ -285,29 +286,6 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> return 0;

You seem to ignore state->polarity which is wrong.

> }
>
> -static int pca9685_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> -{
> - struct pca9685 *pca = to_pca(chip);
> -
> - /*
> - * Clear the full-off bit.
> - * It has precedence over the others and must be off.
> - */
> - regmap_update_bits(pca->regmap, LED_N_OFF_H(pwm->hwpwm), LED_FULL, 0x0);
> -
> - return 0;
> -}
> -
> -static void pca9685_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> -{
> - struct pca9685 *pca = to_pca(chip);
> -
> - regmap_write(pca->regmap, LED_N_OFF_H(pwm->hwpwm), LED_FULL);
> -
> - /* Clear the LED_OFF counter. */
> - regmap_write(pca->regmap, LED_N_OFF_L(pwm->hwpwm), 0x0);
> -}
> -
> static int pca9685_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> {
> struct pca9685 *pca = to_pca(chip);
> @@ -321,14 +299,11 @@ static int pca9685_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
>
> static void pca9685_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
> {
> - pca9685_pwm_disable(chip, pwm);
> pm_runtime_put(chip->dev);
> }
>
> static const struct pwm_ops pca9685_pwm_ops = {
> - .enable = pca9685_pwm_enable,
> - .disable = pca9685_pwm_disable,
> - .config = pca9685_pwm_config,
> + .apply = pca9685_pwm_apply,
> .request = pca9685_pwm_request,
> .free = pca9685_pwm_free,
> .owner = THIS_MODULE,
> @@ -377,9 +352,9 @@ static int pca9685_pwm_probe(struct i2c_client *client,
>
> regmap_write(pca->regmap, PCA9685_MODE2, mode2);
>
> - /* clear all "full off" bits */
> + /* Set all LEDs full off */
> regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_L, 0);
> - regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_H, 0);
> + regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_H, LED_FULL);

This looks wrong or at least unrelated?

Best regards
Uwe

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