From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lukas Wunner Subject: Re: [PATCH v3 0/2] Exynos IOMMU: proper runtime PM support (use device dependencies) Date: Fri, 23 Sep 2016 15:50:02 +0200 Message-ID: <20160923135002.GB4077@wunner.de> References: <57E05C68.80804@math.uni-bielefeld.de> <6114649.EDczdxzVVo@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <6114649.EDczdxzVVo-sKB8Sp2ER+y1GS7QM15AGw@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "Rafael J. Wysocki" Cc: Krzysztof Kozlowski , linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Tomeu Vizoso , linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "Luis R. Rodriguez" , Bartlomiej Zolnierkiewicz , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Inki Dae , Tobias Jakobi , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Kukjin Kim , Mark Brown , Greg Kroah-Hartman , Kevin Hilman List-Id: iommu@lists.linux-foundation.org On Fri, Sep 23, 2016 at 02:49:20PM +0200, Rafael J. Wysocki wrote: > On Tuesday, September 20, 2016 10:51:13 AM Marek Szyprowski wrote: > > On 2016-09-19 23:45, Tobias Jakobi wrote: > > > I did some tests with the new version today. Sadly the reboot/shutdown > > > issues are still present. > > > > Thanks for the report. I've managed to reproduce this issue and it is again > > caused by modifying device on devices_kset list before it will be finally > > added by device_add(). I thought that the new patchset allows creating > > links to a device, which has not been yet added to system device list. Hm, Marek, why isn't it possible to set up the links from the consumer's ->probe hook in this case? > > Should it be allowed to create a link to device, which > > has not yet been added to system device list by device_add()? > > While it would be easy to require both the consumer and producer devices to > be registered for creating a link between them, that would just make it > harder to use links in the first place. > > So ideally, it should be possible to create links between devices before > registering them, but since I didn't take that into account in the current > patch series, some quite substantial changes are needed to cover that. > > Additional link states come to mind, but then the "stateless" links are > affected by this problem too. device_link_add() could be changed to call device_reorder_to_tail() only if device_is_registered(consumer) returns true. That's an inline function defined in which returns dev->kobj.state_in_sysfs, a flag which is set in kobject_add(). Then device_add() would have to check if any links are already set up and reorder the consumer behind the suppliers. Doesn't seem to be *that* complex, but probably I'm missing something, this is just off the cuff... Best regards, Lukas