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

Matthias Schiffer
2020-02-26T13:53:10Z

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;
}

-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);

/*
* The PWM subsystem does not support a pre-delay.
--
2.17.1