From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DE140C10F13 for ; Mon, 8 Apr 2019 18:23:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B3BCB20830 for ; Mon, 8 Apr 2019 18:23:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728640AbfDHSXT (ORCPT ); Mon, 8 Apr 2019 14:23:19 -0400 Received: from mga04.intel.com ([192.55.52.120]:56792 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726369AbfDHSXT (ORCPT ); Mon, 8 Apr 2019 14:23:19 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 Apr 2019 11:23:14 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,326,1549958400"; d="scan'208";a="147550354" Received: from wfang3-mobl.amr.corp.intel.com (HELO [10.254.107.245]) ([10.254.107.245]) by FMSMGA003.fm.intel.com with ESMTP; 08 Apr 2019 11:23:13 -0700 Subject: Re: [alsa-devel] [PATCH] soundwire: fix pm_runtime_get_sync return code checks To: Jan Kotas Cc: "alsa-devel@alsa-project.org" , "linux-kernel@vger.kernel.org" , "vkoul@kernel.org" , Srinivas Kandagatla , "sanyog.r.kale@intel.com" References: <20190405072655.25995-1-jank@cadence.com> <367316fa-9d92-2dfc-32c4-3e0e8c76ef43@linux.intel.com> <92538D7E-C628-40AC-AFE9-52C97B3BC42D@global.cadence.com> From: Pierre-Louis Bossart Message-ID: Date: Mon, 8 Apr 2019 12:43:47 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <92538D7E-C628-40AC-AFE9-52C97B3BC42D@global.cadence.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/8/19 2:12 AM, Jan Kotas wrote: > > >> On 5 Apr 2019, at 17:04, Pierre-Louis Bossart wrote: >> >> On 4/5/19 2:26 AM, Jan Kotas wrote: >>> >>> >>> ret = pm_runtime_get_sync(slave->bus->dev); >>> - if (ret < 0) >>> + if (ret < 0 && ret != -EACCES) >>> >> There was a patch submitted on 3/28 by Srinivas Kandagatla who suggested an alternate solution for exactly the same code. >> >> + if (pm_runtime_enabled(slave->bus->dev)) { >> + ret = pm_runtime_get_sync(slave->bus->dev); >> + if (ret < 0) >> + return ret; >> >> I am far from an expert on pm_runtime but Srinivas' solution looks more elegant to me. > > Hello Pierre, > > Please take a look at this patch, that was my inspiration: > https://lists.linuxfoundation.org/pipermail/linux-pm/2011-June/031930.html The two patches seems to be identical: static inline bool pm_runtime_enabled(struct device *dev) { return !dev->power.disable_depth; } static int rpm_resume() [...] else if (dev->power.disable_depth > 0) retval = -EACCES; However I am still not clear on why this might fail. I can only think of one possible explanation: there is no explicit pm_runtime_enable() in the soundwire code, so maybe the expectation is that the pm_runtime status is inherited from the parent (in the intel case the PCI driver), and that's missing in non-intel configurations? > I also took a look, and it seems the value returned by > pm_runtime_get_syncis simply ignored in a lot of places, > so checking its value may be excessive. But not checking seems careless at best...