From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: [PATCH] ARM: OMAP2+: Fix dmtimer set source clock failure Date: Tue, 07 Aug 2012 11:21:40 -0700 Message-ID: <87boim36mj.fsf@ti.com> References: <1342210323-2129-1-git-send-email-jon-hunter@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from na3sys009aog107.obsmtp.com ([74.125.149.197]:35714 "EHLO na3sys009aog107.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753016Ab2HGSVl (ORCPT ); Tue, 7 Aug 2012 14:21:41 -0400 Received: by pbbrq13 with SMTP id rq13so46462pbb.22 for ; Tue, 07 Aug 2012 11:21:40 -0700 (PDT) In-Reply-To: <1342210323-2129-1-git-send-email-jon-hunter@ti.com> (Jon Hunter's message of "Fri, 13 Jul 2012 15:12:03 -0500") Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Jon Hunter Cc: Tarun Kanti DebBarma , Tony Lindgren , linux-omap , linux-arm Jon Hunter writes: > Calling the dmtimer function omap_dm_timer_set_source() fails if following a > call to pm_runtime_put() to disable the timer. For example the following > sequence would fail to set the parent clock ... > > omap_dm_timer_stop(gptimer); > omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_32_KHZ); > > The following error message would be seen ... > > omap_dm_timer_set_source: failed to set timer_32k_ck as parent > > The problem is that, by design, pm_runtime_put() simply decrements the usage > count and returns before the timer has actually been disabled. Therefore, > setting the parent clock failed because the timer was still active when the > trying to set the parent clock. Setting a parent clock will fail if the clock > you are setting the parent of has a non-zero usage count. To ensure that this > does not fail use pm_runtime_put_sync() when disabling the timer. > > Note that this will not be seen on OMAP1 devices, because these devices do > not use the clock framework for dmtimers. > > Signed-off-by: Jon Hunter Acked-by: Kevin Hilman > --- > arch/arm/plat-omap/dmtimer.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/plat-omap/dmtimer.c b/arch/arm/plat-omap/dmtimer.c > index 626ad8c..7b6689a 100644 > --- a/arch/arm/plat-omap/dmtimer.c > +++ b/arch/arm/plat-omap/dmtimer.c > @@ -258,7 +258,7 @@ EXPORT_SYMBOL_GPL(omap_dm_timer_enable); > > void omap_dm_timer_disable(struct omap_dm_timer *timer) > { > - pm_runtime_put(&timer->pdev->dev); > + pm_runtime_put_sync(&timer->pdev->dev); > } > EXPORT_SYMBOL_GPL(omap_dm_timer_disable); From mboxrd@z Thu Jan 1 00:00:00 1970 From: khilman@ti.com (Kevin Hilman) Date: Tue, 07 Aug 2012 11:21:40 -0700 Subject: [PATCH] ARM: OMAP2+: Fix dmtimer set source clock failure In-Reply-To: <1342210323-2129-1-git-send-email-jon-hunter@ti.com> (Jon Hunter's message of "Fri, 13 Jul 2012 15:12:03 -0500") References: <1342210323-2129-1-git-send-email-jon-hunter@ti.com> Message-ID: <87boim36mj.fsf@ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Jon Hunter writes: > Calling the dmtimer function omap_dm_timer_set_source() fails if following a > call to pm_runtime_put() to disable the timer. For example the following > sequence would fail to set the parent clock ... > > omap_dm_timer_stop(gptimer); > omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_32_KHZ); > > The following error message would be seen ... > > omap_dm_timer_set_source: failed to set timer_32k_ck as parent > > The problem is that, by design, pm_runtime_put() simply decrements the usage > count and returns before the timer has actually been disabled. Therefore, > setting the parent clock failed because the timer was still active when the > trying to set the parent clock. Setting a parent clock will fail if the clock > you are setting the parent of has a non-zero usage count. To ensure that this > does not fail use pm_runtime_put_sync() when disabling the timer. > > Note that this will not be seen on OMAP1 devices, because these devices do > not use the clock framework for dmtimers. > > Signed-off-by: Jon Hunter Acked-by: Kevin Hilman > --- > arch/arm/plat-omap/dmtimer.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/plat-omap/dmtimer.c b/arch/arm/plat-omap/dmtimer.c > index 626ad8c..7b6689a 100644 > --- a/arch/arm/plat-omap/dmtimer.c > +++ b/arch/arm/plat-omap/dmtimer.c > @@ -258,7 +258,7 @@ EXPORT_SYMBOL_GPL(omap_dm_timer_enable); > > void omap_dm_timer_disable(struct omap_dm_timer *timer) > { > - pm_runtime_put(&timer->pdev->dev); > + pm_runtime_put_sync(&timer->pdev->dev); > } > EXPORT_SYMBOL_GPL(omap_dm_timer_disable);