From: Thierry Reding <thierry.reding@gmail.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Bryan Wu <cooloney@gmail.com>, Richard Purdie <rpurdie@rpsys.net>,
linux-leds@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
kernel@pengutronix.de, Shawn Guo <shawn.guo@linaro.org>,
Matt Sealey <matt@genesi-usa.com>
Subject: Re: [PATCH 2/3] leds/pwm: Don't disable pwm when setting brightness to 0
Date: Mon, 2 Dec 2013 13:33:19 +0100 [thread overview]
Message-ID: <20131202123318.GC12793@ulmo.nvidia.com> (raw)
In-Reply-To: <1385412225-29740-3-git-send-email-u.kleine-koenig@pengutronix.de>
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On Mon, Nov 25, 2013 at 09:43:44PM +0100, Uwe Kleine-König 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.
>
> Also only call pwm_enable only once in the probe call back and the
> matching pwm_disable in .remove(). Moreover the pwm is explicitly
> initialized to off.
While I do understand the reasoning behind this, if this is really the
behaviour that we need then there's no use in having pwm_enable() and
pwm_disable() at all. They can just be folded into pwm_get() and
pwm_put(), respectively.
Thierry
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next prev parent reply other threads:[~2013-12-02 12:34 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-25 20:43 [PATCH 0/3] leds/pwm: don't call pwm_disable when setting brightness Uwe Kleine-König
2013-11-25 20:43 ` [PATCH 1/3] pwm/doc: Clearify that the pin state after pwm_disable is undefined Uwe Kleine-König
2013-11-25 20:43 ` [PATCH 2/3] leds/pwm: Don't disable pwm when setting brightness to 0 Uwe Kleine-König
2013-12-02 12:33 ` Thierry Reding [this message]
2013-12-02 13:18 ` Uwe Kleine-König
2013-12-05 21:26 ` Uwe Kleine-König
2013-12-11 15:30 ` Thierry Reding
2013-12-12 21:10 ` Uwe Kleine-König
2013-11-25 20:43 ` [PATCH 3/3] leds/pwm: fix driver description and make license match the header Uwe Kleine-König
2015-11-19 19:17 ` Uwe Kleine-König
2015-11-20 9:36 ` Jacek Anaszewski
2014-02-21 14:15 ` [PATCH 0/3] leds/pwm: don't call pwm_disable when setting brightness Uwe Kleine-König
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