Subject: MX28: leds/pwm: Using pwm driven led as heartbeat leads to kernel warning

From: [email-masked] (Alexandre Belloni)
Date: Fri, 4 Apr 2014 18:44:47 +0200

On 04/04/2014 at 22:26:58 +0800, Shawn Guo wrote :
> On Fri, Apr 04, 2014 at 03:54:52PM +0200, Stefan Wahren wrote:
> > the problem is still reproducable in Mainline 3.14.0 and gives the same
> > warning message.
> > Also i add linux-leds in CC.
> > 
> > Are there any advices to narrow down the problem?
> > 
> > Is this problem specific to i.MX28 PWM (i don't have other kind of
> > hardware)?
> 
> I don't think it's specific to i.MX28 PWM.  Since the .config hook of
> pwm_ops will be called from interrupt context in this case, any pwm
> drivers that do sleeping calls in the hook will have this problem, e.g.
> the clk APIs that hold mutex like clk_prepare() and clk_get_rate() etc.
> 

Yeah, I'm wondering whether we should set pwm->chip->can_sleep then.

Thierry, do you have an opinion ?

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com