heartbeat for leds on i2c bus

heartbeat for leds on i2c bus

[Rodolfo Giometti]

Hello,

on my custom board I have some leds mapped on a dedicated chip
connected via i2c bus.

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?

Thanks in advance,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti@enneenne.com
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Embedded Systems                     		giometti@linux.it
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Re: heartbeat for leds on i2c bus

[Atsushi Nemoto]

On Mon, 3 Dec 2007 11:35:57 +0100, Rodolfo Giometti <giometti@enneenne.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