From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH] ARM: OMAP2+: omap_device: add fail hook for runtime_pm when bad data is detected Date: Tue, 10 Dec 2013 09:30:34 -0800 Message-ID: <20131210173033.GJ13171@atomide.com> References: <1386121153-32351-1-git-send-email-nm@ti.com> <20131205190343.GI26766@atomide.com> <87mwka80vu.fsf@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <87mwka80vu.fsf@linaro.org> Sender: linux-kernel-owner@vger.kernel.org To: Kevin Hilman Cc: Nishanth Menon , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Tobias Jakobi , Joel F List-Id: linux-omap@vger.kernel.org * Kevin Hilman [131209 08:07]: > Tony Lindgren writes: > > > * Nishanth Menon [131203 17:40]: > >> 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. > > > > Kevin, any comments on this one? > > Looks like a good approach to catch these corner cases. > > Acked-by: Kevin Hilman Kevin, care to apply this directly? Acked-by: Tony Lindgren