[PATCH] RFC: leds-pwm: don't disable pwm when setting brightness to 0
From: Shawn Guo <hidden>
Date: 2012-10-25 08:04:00
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On Wed, Oct 24, 2012 at 03:52:46PM +0200, Uwe Kleine-K?nig wrote:
This fixes disabling the LED on i.MX28. The PWM hardware delays using the newly set pwm-config until the beginning of a new period. It's very likely that pwm_disable is called before the current period ends. In case the LED was on brightness=max before the LED stays on because in the disabled PWM block the period never ends. It's unclear if the mxs-pwm driver doesn't implement the API as expected (i.e. it should block until the newly set config is effective) or if the leds-pwm driver makes wrong assumptions. This patch assumes the latter. Signed-off-by: Uwe Kleine-K?nig <redacted> --- Hello, I'm not sure this is correct, but this is the workaround I'm using until I get some feed back.
I'm fine with it, since it fixes a real problem. Let's see what Thierry says. Shawn
quoted hunk ↗ jump to hunk
Best regards Uwe drivers/leds/leds-pwm.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-)diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c index f2e44c7..a909f4f 100644 --- a/drivers/leds/leds-pwm.c +++ b/drivers/leds/leds-pwm.c@@ -38,13 +38,8 @@ static void led_pwm_set(struct led_classdev *led_cdev, unsigned int max = led_dat->cdev.max_brightness; unsigned int period = led_dat->period; - if (brightness == 0) { - pwm_config(led_dat->pwm, 0, period); - pwm_disable(led_dat->pwm); - } else { - pwm_config(led_dat->pwm, brightness * period / max, period); - pwm_enable(led_dat->pwm); - } + pwm_config(led_dat->pwm, brightness * period / max, period); + pwm_enable(led_dat->pwm); } static int led_pwm_probe(struct platform_device *pdev)-- 1.7.10.4