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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 280CFC4332F for ; Wed, 4 Jan 2023 13:14:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239351AbjADNOZ (ORCPT ); Wed, 4 Jan 2023 08:14:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53036 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239496AbjADNNm (ORCPT ); Wed, 4 Jan 2023 08:13:42 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 7A7A03B911; Wed, 4 Jan 2023 05:11:17 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BD30D1063; Wed, 4 Jan 2023 05:11:58 -0800 (PST) Received: from [10.57.42.13] (unknown [10.57.42.13]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1B8B53F587; Wed, 4 Jan 2023 05:11:14 -0800 (PST) Message-ID: <9a86f7cd-2dce-f27a-af21-d64318ca3ef7@arm.com> Date: Wed, 4 Jan 2023 13:11:13 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Subject: Re: [PATCH] coresight: cti: Add PM runtime call in enable_store Content-Language: en-US To: Mao Jinlong Cc: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Tingwei , Yuanfang Zhang , Tao Zhang , Hao Zhang , linux-arm-msm@vger.kernel.org, Mathieu Poirier , Suzuki K Poulose , Mike Leach , Leo Yan , Alexander Shishkin , Suzuki K Poulose References: <20221224141700.20891-1-quic_jinlmao@quicinc.com> From: James Clark In-Reply-To: <20221224141700.20891-1-quic_jinlmao@quicinc.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/12/2022 14:17, Mao Jinlong wrote: > In commit 6746eae4bbad ("coresight: cti: Fix hang in cti_disable_hw()") > PM runtime calls are removed from cti_enable_hw/cti_disable_hw. When > enabling CTI by writing enable sysfs node, clock for accessing CTI > register won't be enabled. Device will crash due to register access > issue. Add PM runtime call in enable_store to fix this issue. > > Signed-off-by: Mao Jinlong > --- > drivers/hwtracing/coresight/coresight-cti-sysfs.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c > index 6d59c815ecf5..b1ed424ae043 100644 > --- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c > +++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c > @@ -108,10 +108,17 @@ static ssize_t enable_store(struct device *dev, > if (ret) > return ret; > > - if (val) > + if (val) { > + ret = pm_runtime_resume_and_get(dev->parent); > + if (ret) > + return ret; > ret = cti_enable(drvdata->csdev); > - else > + if (ret) > + pm_runtime_put(dev->parent); > + } else { > ret = cti_disable(drvdata->csdev); > + pm_runtime_put(dev->parent); Hi Jinlong, This new pm_runtime_put() causes this when writing 0 to enable: [ 483.253814] coresight-cti 23020000.cti: Runtime PM usage count underflow! Maybe we can modify cti_disable_hw() to return a value to indicate that the disable actually happened, and only then call pm_runtime_put(). I suppose you could also check in the store function if it was already enabled first, but then I don't know what kind of locking that would need? cti_disable_hw() already seems to have a couple of locks, so maybe the return value solution is easiest. Thanks James