From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joel Fernandes Subject: Re: [PATCH] ARM: OMAP2+: omap_device: add fail hook for runtime_pm when bad data is detected Date: Wed, 4 Dec 2013 13:38:37 +0530 Message-ID: <529EE305.70001@ti.com> References: <1386121153-32351-1-git-send-email-nm@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from devils.ext.ti.com ([198.47.26.153]:43655 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753735Ab3LDIJK (ORCPT ); Wed, 4 Dec 2013 03:09:10 -0500 In-Reply-To: <1386121153-32351-1-git-send-email-nm@ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Nishanth Menon , Tony Lindgren Cc: linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Tobias Jakobi On 12/04/2013 07:09 AM, Nishanth Menon wrote: > Due to the cross dependencies between hwmod for automanaged device > information for OMAP and dts node definitions, we can run into scenarios > where the dts node is defined, however it's hwmod entry is yet to be > added. In these cases: > a) omap_device does not register a pm_domain (since it cannot find > hwmod entry). > b) driver does not know about (a), does a pm_runtime_get_sync which > never fails > c) It then tries to do some operation on the device (such as read the > revision register (as part of probe) without clock or adequate OMAP > generic PM operation performed for enabling the module. > > This causes a crash such as that reported in: > https://bugzilla.kernel.org/show_bug.cgi?id=66441 > > When 'ti,hwmod' is provided in dt node, it is expected that the device > will not function without the OMAP's power automanagement. Hence, when > we hit a fail condition (due to hwmod entries not present or other > similar scenario), fail at pm_domain level due to lack of data, provide > enough information for it to be fixed, however, it allows for the driver > to take appropriate measures to prevent crash. > > Reported-by: Tobias Jakobi > Signed-off-by: Nishanth Menon > --- > arch/arm/mach-omap2/omap_device.c | 24 ++++++++++++++++++++++++ > arch/arm/mach-omap2/omap_device.h | 1 + > 2 files changed, 25 insertions(+) > > diff --git a/arch/arm/mach-omap2/omap_device.c b/arch/arm/mach-omap2/omap_device.c > index 53f0735..e0a398c 100644 > --- a/arch/arm/mach-omap2/omap_device.c > +++ b/arch/arm/mach-omap2/omap_device.c > @@ -183,6 +183,10 @@ static int omap_device_build_from_dt(struct platform_device *pdev) > odbfd_exit1: > kfree(hwmods); > odbfd_exit: > + /* if data/we are at fault.. load up a fail handler */ > + if (ret) > + pdev->dev.pm_domain = &omap_device_fail_pm_domain; > + > return ret; > } > Just wondering, can't we just print the warning here instead of registering new pm_domain callbacks? Concerned that all this LOC may end up being dead code when the "ti,hwmods" property becomes obsolete anyway. -Joel