From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexandre Belloni Subject: Re: MX28: leds/pwm: Using pwm driven led as heartbeat leads to kernel warning Date: Fri, 4 Apr 2014 18:44:47 +0200 Message-ID: <20140404164446.GI4883@piout.net> References: <53345C93.9040005@i2se.com> <533EB9AC.6040708@i2se.com> <20140404142656.GA16383@dragon> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from top.free-electrons.com ([176.31.233.9]:39913 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753049AbaDDQot (ORCPT ); Fri, 4 Apr 2014 12:44:49 -0400 Content-Disposition: inline In-Reply-To: <20140404142656.GA16383@dragon> Sender: linux-pwm-owner@vger.kernel.org List-Id: linux-pwm@vger.kernel.org To: Shawn Guo Cc: Stefan Wahren , Fabio Estevam , Thierry Reding , Bryan Wu , Richard Purdie , Sascha Hauer , linux-arm-kernel@lists.infradead.org, linux-pwm@vger.kernel.org, linux-leds@vger.kernel.org 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