Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754544Ab2FSOsZ (ORCPT ); Tue, 19 Jun 2012 10:48:25 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:50597 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751786Ab2FSOsX (ORCPT ); Tue, 19 Jun 2012 10:48:23 -0400 Date: Tue, 19 Jun 2012 10:48:22 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: chao xie cc: linux-pm@vger.kernel.org, , , , Subject: Re: pm runtime and system suspend resume In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1906 Lines: 48 On Tue, 19 Jun 2012, chao xie wrote: > hi > PM_RUNTIME provide a way for device driver do runtime PM. so for some > devices, they have some surrounded logic. For example, the device may > get clock from outside, or it need PHY support(USB is a example). > To get these dependency out of device driver, i define a struct > dev_pm_domain, and make dev.pm_domain point to it. So in the device > driver, when the hardware should be enabled, we can call > pm_runtime_get_sync while when the hardware is idle or does not work, > we can call pm_runtime_put_sync. > It seems work well, but i have question about the suspend/resume of > device. When the whole system will go to deep idle, and it will > suspend the devices. for the function do device suspend > __device_suspend, What source file is that function in? > it will call pm_runtime_get_noresume(dev). As i > think it will make the device not do runtime suspend any more. Is that > correct? It sounds wrong. Why would a suspend routine do that? > There is the question, how device driver handle the logic surrounds > it? I want to add pm_runtime_put_sync in dev->driver->pm->suspend > function, and pm_runtime_get_sync in dev->driver->pm->resume. You must not do that. If you do, your driver will hang. > Because > __device_suspend increase the usage_count, pm_runtime_put_sync will > not do real work. > So is that right that i directly call pm_runtime_suspend in > dev->driver->pm->suspend and pm_runtime_resume in > dev->driver->pm->resume? No, it works the other way around. pm_runtime_suspend calls dev->driver->pm->suspend, and pm_runtime_resume calls dev->driver->pm->resume. Alan Stern -- 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/