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From: Florian Vaussard <florian.vaussard-p8DiymsW2f8@public.gmane.org>
To: Peter Ujfalusi <peter.ujfalusi-l0cyMroinI0@public.gmane.org>
Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
	linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [PATCH 1/2] ARM: dts: omap3-overo: Add support for pwm-leds
Date: Thu, 24 Jan 2013 22:14:37 +0100	[thread overview]
Message-ID: <5101A43D.7080108@epfl.ch> (raw)
In-Reply-To: <51016A84.20703-l0cyMroinI0@public.gmane.org>

Hi

>>
>>>> I am working on a patch for pwm-twl-led to defer using a workqueue right now.
>>>
>>> Great!
>>> The only thing I worry about is the latency we are going to get with the
>>> workqueue.
>>>
>>
>> If the latency becomes critical, we can create our own workqueue.
>
> Hrm, when we handled the led via gpio-leds it was also going through the same
> path at the end, via i2c to twl4030.
> I think the fix for this is going to be needed in the pwm core level. Just
> need to look at the gpio code to have similar handling of might_sleep interfaces.
>

You are right. But then the pwm core must provide a way to know if the 
pwm access function are callable
from atomic context or not (the gpio framework provides gpio_cansleep()).
This implies a good amount of changes to the pwm framework, and 
currently we are the only driver using
non-atomic access.

I will take a closer look to the complexity of this solution tomorrow.

Florian

WARNING: multiple messages have this Message-ID (diff)
From: florian.vaussard@epfl.ch (Florian Vaussard)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] ARM: dts: omap3-overo: Add support for pwm-leds
Date: Thu, 24 Jan 2013 22:14:37 +0100	[thread overview]
Message-ID: <5101A43D.7080108@epfl.ch> (raw)
In-Reply-To: <51016A84.20703@ti.com>

Hi

>>
>>>> I am working on a patch for pwm-twl-led to defer using a workqueue right now.
>>>
>>> Great!
>>> The only thing I worry about is the latency we are going to get with the
>>> workqueue.
>>>
>>
>> If the latency becomes critical, we can create our own workqueue.
>
> Hrm, when we handled the led via gpio-leds it was also going through the same
> path at the end, via i2c to twl4030.
> I think the fix for this is going to be needed in the pwm core level. Just
> need to look at the gpio code to have similar handling of might_sleep interfaces.
>

You are right. But then the pwm core must provide a way to know if the 
pwm access function are callable
from atomic context or not (the gpio framework provides gpio_cansleep()).
This implies a good amount of changes to the pwm framework, and 
currently we are the only driver using
non-atomic access.

I will take a closer look to the complexity of this solution tomorrow.

Florian

  parent reply	other threads:[~2013-01-24 21:14 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-01-23 17:56 [PATCH 0/2] ARM: dts: omap3-overo: Add pwm-leds and audio support Florian Vaussard
2013-01-23 17:56 ` Florian Vaussard
2013-01-23 17:56 ` [PATCH 1/2] ARM: dts: omap3-overo: Add support for pwm-leds Florian Vaussard
2013-01-23 17:56   ` Florian Vaussard
     [not found]   ` <1358963812-19947-2-git-send-email-florian.vaussard-p8DiymsW2f8@public.gmane.org>
2013-01-24 15:19     ` Peter Ujfalusi
2013-01-24 15:19       ` Peter Ujfalusi
2013-01-24 15:42       ` Florian Vaussard
2013-01-24 15:42         ` Florian Vaussard
2013-01-24 15:45         ` Peter Ujfalusi
2013-01-24 15:45           ` Peter Ujfalusi
2013-01-24 16:50           ` Florian Vaussard
2013-01-24 16:50             ` Florian Vaussard
2013-01-24 17:08             ` Peter Ujfalusi
2013-01-24 17:08               ` Peter Ujfalusi
     [not found]               ` <51016A84.20703-l0cyMroinI0@public.gmane.org>
2013-01-24 21:14                 ` Florian Vaussard [this message]
2013-01-24 21:14                   ` Florian Vaussard
2013-01-25  8:29                   ` Peter Ujfalusi
2013-01-25  8:29                     ` Peter Ujfalusi
2013-01-25 12:07                     ` Peter Ujfalusi
2013-01-25 12:07                       ` Peter Ujfalusi
2013-01-25 12:21                       ` Florian Vaussard
2013-01-25 12:21                         ` Florian Vaussard
2013-01-25 12:30                         ` Peter Ujfalusi
2013-01-25 12:30                           ` Peter Ujfalusi
2013-01-23 17:56 ` [PATCH 2/2] ARM: dts: omap3-overo: Add audio support Florian Vaussard
2013-01-23 17:56   ` Florian Vaussard
2013-01-24 15:21   ` Peter Ujfalusi
2013-01-24 15:21     ` Peter Ujfalusi
2013-01-24 12:21 ` [PATCH 0/2] ARM: dts: omap3-overo: Add pwm-leds and " Benoit Cousson
2013-01-24 12:21   ` Benoit Cousson
2013-02-04  9:14   ` Florian Vaussard
2013-02-04  9:14     ` Florian Vaussard
2013-02-06 13:30     ` Benoit Cousson
2013-02-06 13:30       ` Benoit Cousson
2013-02-06 14:26       ` Philippe Rétornaz
2013-02-06 14:26         ` Philippe Rétornaz
2013-02-07  7:58       ` Peter Ujfalusi
2013-02-07  7:58         ` Peter Ujfalusi
2013-02-26 16:07         ` Florian Vaussard
2013-02-26 16:07           ` Florian Vaussard
2013-02-26 16:19           ` Benoit Cousson
2013-02-26 16:19             ` Benoit Cousson

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