From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: Re: [PATCH] pwm: mxs: set pwm_chip can_sleep flag Date: Tue, 8 Apr 2014 19:59:04 +0200 Message-ID: <20140408175904.GT29751@pengutronix.de> References: <1396956597-26159-1-git-send-email-shawn.guo@freescale.com> <5343FDD3.3070308@i2se.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:34487 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932665AbaDHR7I (ORCPT ); Tue, 8 Apr 2014 13:59:08 -0400 Content-Disposition: inline In-Reply-To: <5343FDD3.3070308@i2se.com> Sender: linux-pwm-owner@vger.kernel.org List-Id: linux-pwm@vger.kernel.org To: Stefan Wahren Cc: Shawn Guo , linux-pwm@vger.kernel.org, Thierry Reding , Alexandre Belloni , linux-arm-kernel@lists.infradead.org Hello, On Tue, Apr 08, 2014 at 03:46:59PM +0200, Stefan Wahren wrote: > Am 08.04.2014 13:29, schrieb Shawn Guo: > > The .config() calls clk_get_rate() which might sleep, so we need to= set > > pwm_chip can_sleep flag. Otherwise, we see the following warning w= hen > > using pwm driven heartbeat led. > > > > WARNING: CPU: 0 PID: 0 at kernel/locking/mutex.c:856 mutex_trylock+= 0x184/0x1a4() > > DEBUG_LOCKS_WARN_ON(in_interrupt()) > > Modules linked in: > > CPU: 0 PID: 0 Comm: swapper Not tainted 3.14.0-rc5 #18 > > [] (unwind_backtrace) from [] (show_stack+0x10/= 0x14) > > [] (show_stack) from [] (warn_slowpath_common+0= x6c/0x8c) > > [] (warn_slowpath_common) from [] (warn_slowpat= h_fmt+0x30/0x40) > > [] (warn_slowpath_fmt) from [] (mutex_trylock+0= x184/0x1a4) > > [] (mutex_trylock) from [] (clk_prepare_lock+0x= c/0xec) > > [] (clk_prepare_lock) from [] (clk_get_rate+0xc= /0x68) > > [] (clk_get_rate) from [] (mxs_pwm_config+0x20/= 0x198) > > [] (mxs_pwm_config) from [] (pwm_config+0x60/0x= 70) > > [] (pwm_config) from [] (__led_pwm_set+0x1c/0x3= c) > > [] (__led_pwm_set) from [] (led_heartbeat_funct= ion+0x70/0x110) > > [] (led_heartbeat_function) from [] (call_timer= _fn+0x7c/0x164) > > [] (call_timer_fn) from [] (run_timer_softirq+0= x1f0/0x260) > > [] (run_timer_softirq) from [] (__do_softirq+0x= c4/0x2f0) > > [] (__do_softirq) from [] (irq_exit+0xa4/0x10c) > > [] (irq_exit) from [] (handle_IRQ+0x34/0x84) > > [] (handle_IRQ) from [] (__irq_svc+0x44/0x54) > > [] (__irq_svc) from [] (arch_cpu_idle+0x40/0x48= ) > > [] (arch_cpu_idle) from [] (cpu_startup_entry+0= x70/0x198) > > [] (cpu_startup_entry) from [] (start_kernel+0x= 2a8/0x2f8) > > > > Reported-by: Stefan Wahren > > Signed-off-by: Shawn Guo > > --- > > drivers/pwm/pwm-mxs.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c > > index 9475bc7..4f1bb4e 100644 > > --- a/drivers/pwm/pwm-mxs.c > > +++ b/drivers/pwm/pwm-mxs.c > > @@ -147,6 +147,7 @@ static int mxs_pwm_probe(struct platform_device= *pdev) > > mxs->chip.dev =3D &pdev->dev; > > mxs->chip.ops =3D &mxs_pwm_ops; > > mxs->chip.base =3D -1; > > + mxs->chip.can_sleep =3D true; > > ret =3D of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npw= m); > > if (ret < 0) { > > dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret); >=20 > thanks for the patch. I've tested it with our i.MX28 board and the > warning above never came. So it works. > Unfortunately the led still don't behave as expected. If i set the le= d > trigger to heartbeat the led goes on and stays in this state. >=20 > May be this has something to do with the following discussion >=20 > http://comments.gmane.org/gmane.linux.leds/208 I guess that's your problem, yes. Does patch 2 of my series (i.e. http://thread.gmane.org/gmane.linux.ports.arm.kernel/282593/focus=3D282= 596) help you? Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig = | Industrial Linux Solutions | http://www.pengutronix.de/= |