From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiner Kallweit Subject: Re: [PATCH] usb: storage: fix runtime pm issue in usb_stor_probe2 Date: Thu, 4 Aug 2016 07:34:03 +0200 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alan Stern Cc: Greg Kroah-Hartman , Linux USB Mailing List , SCSI development list , "Martin K. Petersen" List-Id: linux-scsi@vger.kernel.org Am 03.08.2016 um 23:25 schrieb Alan Stern: > On Wed, 3 Aug 2016, Heiner Kallweit wrote: > >> Since commit 71723f95463d "PM / runtime: print error when activating a >> child to unactive parent" I see the following error message: >> >> scsi host2: usb-storage 1-3:1.0 >> scsi host2: runtime PM trying to activate child device host2 but parent >> (1-3:1.0) is not active >> >> Digging into it it seems to be related to the problem described in the >> commit message for cd998ded5c12 "i2c: designware: Prevent runtime >> suspend during adapter registration" as scsi_add_host also calls >> device_add and after the call to device_add the parent device is >> suspended. >> >> Fix this by using the approach from the mentioned commit and getting >> the runtime pm reference before calling scsi_add_host. > > Acked-by: Alan Stern > > There's nothing wrong with this patch; it's a worthwhile thing to do > because it can prevent an unnecessary runtime-suspend/resume cycle. > > Still, it looks like the real problem here may lie in > drivers/scsi/hosts.c. Commit bc4f24014de5 ("[SCSI] implement runtime > Power Management") added a call to pm_runtime_set_active() in > scsi_add_host_with_dma() _after_ device_add() instead of _before_. > > If that were changed, this problem would not have occurred. > In parallel to this patch I sent another one to address exactly the ordering issue in scsi_add_host_with_dma you mention. The other patch went to Martin and the SCSI mailing list only, sorry. I'll forward it to you for review. Heiner > Alan Stern > > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html