From: Sascha Hauer <s.hauer@pengutronix.de>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>,
Sascha Hauer <kernel@pengutronix.de>,
Grant Likely <grant.likely@secretlab.ca>,
linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org
Subject: Re: [PATCH] gpio: twl4030: Use only TWL4030_MODULE_LED for LED configuration
Date: Mon, 19 Nov 2012 11:57:59 +0100 [thread overview]
Message-ID: <20121119105759.GU10369@pengutronix.de> (raw)
In-Reply-To: <CACRpkdbvXFtHoOXThUrT4Z+8nO_HJCFq-May+4zaOsNv-886LA@mail.gmail.com>
On Mon, Nov 19, 2012 at 11:40:30AM +0100, Linus Walleij wrote:
> On Mon, Nov 19, 2012 at 9:52 AM, Peter Ujfalusi <peter.ujfalusi@ti.com> wrote:
>
> > I was actually tempted to remove the whole LED (PWM) thing from the
> > gpio-twl4030 driver. It was a big surprise to me to see something like this in
> > there.
>
> It looks wrong. In theory I think this should be ripped out and moved to
> drivers/leds/leds-twl4030.c. But that would only be in case it was *always*
> exclusively used for a LED and as you say:
>
> > It turns out that on BeagleBoard the USB host enable signal is connected to
> > LEDA (PWMA) of twl4030... It is an enable signal. Seriously. So what we do
> > here is either configure the PWMs as full on, or turn it off.
>
> Sounds like some hardware engineer has been having fun or was
> just out of GPIOs to use... So this LED PWM is also used as a
> GPIO.
>
> I think this part of the driver should be moved to
> drivers/pwm/pwm-twl4030.c and modeled as a PWM. If some
> platform need to use the PWM as if it was a GPIO then that's just a
> special usecase. (Setting duty cycles to something like
> INT_MAX and just switching polarity to toggle it...)
>
> If it needs to be used by a LED there needs to be some generic
> LED type just using a standard pwm_request() to get some
> specific PWM, such as leds/leds-pwm.c or so. This way the
> PWM can be used for LEDs if need be or other things...
Either I'm misinterpreting you or you didn't have a look in the tree.
Actually drivers/leds/leds-pwm.c already exists.
>
> Sounds correct, Sascha?
Yes, the twl4030 pwm should go to drivers/pwm/pwm-twl4030.c.
Sascha
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next prev parent reply other threads:[~2012-11-19 10:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-13 9:35 [PATCH] gpio: twl4030: Use only TWL4030_MODULE_LED for LED configuration Peter Ujfalusi
2012-11-17 20:16 ` Linus Walleij
2012-11-19 8:52 ` Peter Ujfalusi
2012-11-19 10:40 ` Linus Walleij
2012-11-19 10:57 ` Sascha Hauer [this message]
2012-11-19 12:22 ` Peter Ujfalusi
2012-11-19 12:19 ` Peter Ujfalusi
2012-11-20 18:42 ` Linus Walleij
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