linux-kernel - Re: heartbeat for leds on i2c bus

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Message-Id: <20071203.224546.35471256.anemo@mba.ocn.ne.jp>
Date:	Mon, 03 Dec 2007 22:45:46 +0900 (JST)
From:	Atsushi Nemoto <anemo@....ocn.ne.jp>
To:	giometti@...eenne.com
Cc:	linux-kernel@...r.kernel.org
Subject: Re: heartbeat for leds on i2c bus

On Mon, 3 Dec 2007 11:35:57 +0100, Rodolfo Giometti <giometti@...eenne.com> wrote:
> If I try to use the heartbeat trigger I hang the system... I suppose
> it is due the fact the led_set_brightness() function is called inside
> a kernel timer.
> 
> How I can solve this problem? I thought to modify the trigger adding a
> kernel thread who manage the led which in turn is controlled by the
> kernel timer. It could be the right solution?

Yes, the heartbeat trigger driver assumes brightness_set() routine can
be called from timer.  Other led-triggers also have this assumption.

So I'd suggest using workqueue for your led driver, as like as the
leds-gpio driver.  Or you can just use the leds-gpio driver and
implement the gpio interface (gpio_set_value_cansleep) instead of the
led interface.

---
Atsushi Nemoto
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