[PATCH v4 10/16] pwm: crc: Enable/disable PWM output on enable/disable

Hans de Goede
2020-07-08T21:15:31Z

The pwm-crc code is using 2 different enable bits:
1. bit 7 of the PWM0_CLK_DIV (PWM_OUTPUT_ENABLE)
2. bit 0 of the BACKLIGHT_EN register

So far we've kept the PWM_OUTPUT_ENABLE bit set when disabling the PWM,
this commit makes crc_pwm_disable() clear it on disable and makes
crc_pwm_enable() set it again on re-enable.

Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v3:
- Remove paragraph about tri-stating the output from the commit message,
we don't have a datasheet so this was just an unfounded guess
---
drivers/pwm/pwm-crc.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/pwm/pwm-crc.c b/drivers/pwm/pwm-crc.c
index 81232da0c767..b72008c9b072 100644
--- a/drivers/pwm/pwm-crc.c
+++ b/drivers/pwm/pwm-crc.c
@@ -54,7 +54,9 @@ static int crc_pwm_calc_clk_div(int period_ns)
static int crc_pwm_enable(struct pwm_chip *c, struct pwm_device *pwm)
{
struct crystalcove_pwm *crc_pwm = to_crc_pwm(c);
+ int div = crc_pwm_calc_clk_div(pwm_get_period(pwm));

+ regmap_write(crc_pwm->regmap, PWM0_CLK_DIV, div | PWM_OUTPUT_ENABLE);
regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 1);

return 0;
@@ -63,8 +65,10 @@ static int crc_pwm_enable(struct pwm_chip *c, struct pwm_device *pwm)
static void crc_pwm_disable(struct pwm_chip *c, struct pwm_device *pwm)
{
struct crystalcove_pwm *crc_pwm = to_crc_pwm(c);
+ int div = crc_pwm_calc_clk_div(pwm_get_period(pwm));

regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 0);
+ regmap_write(crc_pwm->regmap, PWM0_CLK_DIV, div);
}

static int crc_pwm_config(struct pwm_chip *c, struct pwm_device *pwm,
--
2.26.2