From 45c0ce847a99ca053d432ea98e4ff55d88357d7e Mon Sep 17 00:00:00 2001 From: Paul Kocialkowski Date: Tue, 29 Mar 2016 20:55:45 +0200 Subject: pwm: twl: Reliably disable TWL6030 PWMs The current TWL6030 code for the TWL PWM driver does not reliably disable the PWM output, as tested with LEDs. The previous commit to that driver introduced that regression. However, it does make sense to disable the PWM clock after resetting the PWM, but for some obscure reason, doing it all at once simply doesn't work. The TWL6030 datasheet mentions that PWMs have to be disabled in two distinct steps. However, clearing the clock enable bit in a second step (after issuing a reset first) does not work. The only approach that works is the one that was in place before the previous commit to the driver. It consists in enabling the PWM clock after issuing a reset. This is what TI kernel trees and production code seem to be using. However, adding an extra step to disable the PWM clock seems to work reliably, despite looking quite odd. Signed-off-by: Paul Kocialkowski Acked-by: Peter Ujfalusi Signed-off-by: Thierry Reding --- drivers/pwm/pwm-twl.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'drivers') diff --git a/drivers/pwm/pwm-twl.c b/drivers/pwm/pwm-twl.c index 04f76725d591..7a993b056638 100644 --- a/drivers/pwm/pwm-twl.c +++ b/drivers/pwm/pwm-twl.c @@ -269,6 +269,22 @@ static void twl6030_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) goto out; } + val |= TWL6030_PWM_TOGGLE(pwm->hwpwm, TWL6030_PWMXEN); + + ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, val, TWL6030_TOGGLE3_REG); + if (ret < 0) { + dev_err(chip->dev, "%s: Failed to disable PWM\n", pwm->label); + goto out; + } + + val &= ~TWL6030_PWM_TOGGLE(pwm->hwpwm, TWL6030_PWMXEN); + + ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, val, TWL6030_TOGGLE3_REG); + if (ret < 0) { + dev_err(chip->dev, "%s: Failed to disable PWM\n", pwm->label); + goto out; + } + twl->twl6030_toggle3 = val; out: mutex_unlock(&twl->mutex); -- cgit v1.2.3