From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965655AbbKDQ7r (ORCPT ); Wed, 4 Nov 2015 11:59:47 -0500 Received: from mail-pa0-f44.google.com ([209.85.220.44]:34814 "EHLO mail-pa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932433AbbKDQ7p (ORCPT ); Wed, 4 Nov 2015 11:59:45 -0500 From: Kevin Hilman To: Vinod Koul Cc: "Rafael J. Wysocki" , Jon Hunter , Laxman Dewangan , Stephen Warren , Thierry Reding , Alexandre Courbot , dmaengine@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/6] dmaengine: tegra-apb: Correct runtime-pm usage References: <1444983957-18691-1-git-send-email-jonathanh@nvidia.com> <1444983957-18691-2-git-send-email-jonathanh@nvidia.com> <20151028070345.GF3041@vkoul-mobl.iind.intel.com> <5630CE5C.7070201@nvidia.com> <20151029015709.GE18368@vkoul-mobl.iind.intel.com> <5638DF7E.9080700@nvidia.com> <7hvb9iai8a.fsf@deeprootsystems.com> <20151104083438.GJ12910@localhost> Date: Wed, 04 Nov 2015 08:59:43 -0800 In-Reply-To: <20151104083438.GJ12910@localhost> (Vinod Koul's message of "Wed, 4 Nov 2015 14:04:38 +0530") Message-ID: <7hvb9hr98g.fsf@deeprootsystems.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Vinod Koul writes: > On Tue, Nov 03, 2015 at 01:25:09PM -0800, Kevin Hilman wrote: >> >>>>> /* Enable clock before accessing register */ >> >>>>> - ret = tegra_dma_runtime_resume(dev); >> >>>>> + ret = pm_runtime_get_sync(dev); >> >>>> >> >>>> If you are runtime suspended then core will runtime resume you before >> >>>> invoking suspend, so why do we need this >> >>> >> >>> Is this change now in the mainline? Do you have commit ID for that? >> >>> >> >>> I recall the last time we discussed this that Rafael said that they were >> >>> going to do that, but he said as a rule of thumb if you need to resume >> >>> it, resume it [0]. >> >> >> >> IIRC this has been always the behaviour, at least I see this when I test the >> >> devices >> > >> > I have been doing some testing today and if the DMA is runtime >> > suspended, then I don't see it runtime resumed before suspend is called. >> > >> > Can you elborate on "at least I see this when I test the devices"? What >> > are you looking at? Are you using kernel function tracers in some way? >> >> The PM core does a _get_noresume()[1] which tries to prevent runtime >> suspends *during* a system suspend. However, the PM core should not be >> doing an actual runtime resume of the device, so if the device is >> already runtime suspended, it will not be runtime resumed by the core, >> so if the driver needs it to be runtime resumed, it needs to do it >> itself. > > + Rafael > > This is contrariry to what I see, If my driver is runtime suspended and on > suspend, it gets runtime resumed and then suspended Since I was late to the thread, can you explain what kind of driver and on what bus type you're seeing this behavior? It could be that your bus-type is doing something, but I don't think it should be the PM core. Kevin