Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965376Ab3FTMc3 (ORCPT ); Thu, 20 Jun 2013 08:32:29 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:44105 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965031Ab3FTMc1 (ORCPT ); Thu, 20 Jun 2013 08:32:27 -0400 Message-ID: <51C2F641.9000803@ti.com> Date: Thu, 20 Jun 2013 15:32:01 +0300 From: Roger Quadros User-Agent: Mozilla/5.0 (X11; Linux i686; rv:16.0) Gecko/20121011 Thunderbird/16.0.1 MIME-Version: 1.0 To: Kevin Hilman CC: , , , , , , , Subject: Re: [RFC PATCH 4/6] USB: ehci-omap: Suspend the controller during bus suspend References: <1371650753-11452-1-git-send-email-rogerq@ti.com> <1371650753-11452-5-git-send-email-rogerq@ti.com> <87r4fy6lvm.fsf@linaro.org> In-Reply-To: <87r4fy6lvm.fsf@linaro.org> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1654 Lines: 39 On 06/19/2013 08:39 PM, Kevin Hilman wrote: > Hi Roger, > > Roger Quadros writes: > >> Runtime suspend the controller during bus suspend and resume it >> during bus resume. This will ensure that the USB Host power domain >> enters lower power state and does not prevent the SoC from >> endering deeper sleep states. >> >> Remote wakeup will come up as an interrupt while the controller >> is suspended, so tackle it carefully using a workqueue. > > I don't think you need a special workqueue here. The workqueue of the PM > core (pm_wq) will be used if you just use an asynchronous 'get' in the > ISR. Then, the driver's own runtime PM callbacks can be used instead of > an additional workqueue. > > Another thing to worry about here when using runtime PM to implement > suspend/resume is that runtime PM can be disabled from userspace (e.g. > echo disabled > /sys/devices/.../power/control.) If that's the case, > all the pm_runtime_suspended() checks will always fail becuase that > call also checks if runtime PM is disabled. You'll likely want to use > the pm_runtime_status_suspended() check instead, which checks only the > status, and doesn't matter if runtime PM is currently disabled. > > Because of the corner issues here, please test system suspend/resume > when runtime PM has been disabled. > Good points. Thanks. I'll need to think about it some more. cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/