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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-380e15e6e33sm86819a91.5.2026.07.01.17.59.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 01 Jul 2026 17:59:04 -0700 (PDT) Message-ID: <5218878b-c91f-4d14-ba12-68edf7b3f4a7@oss.qualcomm.com> Date: Thu, 2 Jul 2026 08:59:00 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] coresight: Fix clock refcount imbalance on platform remove To: Leo Yan Cc: Suzuki K Poulose , Mike Leach , James Clark , Alexander Shishkin , Anshuman Khandual , Yeoreum Yun , Yuanfang Zhang , Maxime Coquelin , Alexandre Torgue , Tingwei Zhang , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com References: <20260701-fix-clock-refcount-unbalance-v1-0-321dc63c1f90@oss.qualcomm.com> <20260701-fix-clock-refcount-unbalance-v1-1-321dc63c1f90@oss.qualcomm.com> <20260701162321.GG1812158@e132581.arm.com> Content-Language: en-US From: Jie Gan In-Reply-To: <20260701162321.GG1812158@e132581.arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-Spam-Info: AW1haW4tMjYwNzAyMDAwNyBTYWx0ZWRfX+ulUlyuyUA6+ FYWzTmIeNYAGZi6541EozWdgAmIpbcnuU3p4fyUGy10Dnnw7DGffDOJ/1lGrfv0CimuSehrRXiR fjoQ6C7AR01nIYeZIkCBmXJK3ByZLCw= X-Proofpoint-GUID: ubOkiGaYQJ0yYY5tm4z6xPQ7kt2_Dvnn X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzAyMDAwNyBTYWx0ZWRfX2wEdWkwRjuHl fY4ealh/SAhefuoaEYeG7SxsoaZFuq464OHke/8n7LI+1pVbZF29bfrRZVSp4gBfIQ+bzAdKCRn DtrAYtCeaYE5AXDM1gIHq9TfiGPQ2s5pOv+bN4FXVTCjInI4Wo0bZrN+b+oGFeayrMT0d/x+DFz ikjXnN2rvwCgiazOAkaoBLAZgZA8AIJyFxz6ebctUZQ8YHIVcAjbHSRIdcbF9rCENoANoVPm6uB DI3NxjnZltfW8ivUz1fOrYXXL2l3ZMTxc5ZbnH2q5jUfYNbHtdXyxuph3JDhtIStAznpMk5kzxK 9m9p3pUtwOFOyTEJwMk07FW8npvGmFGv8EistEDP36uwTtiS1ljfWMsu56CGJd+bhj7nOjFGxH4 pYoSD6wdfhNRjV7TepX4QfmxI6eN2Z0cgsxTIkaqApgt9ikkeErF9Z+HV/bWkJWV7etz1NOSVnT ovD/SOzeXpzfu2I9qbQ== X-Proofpoint-ORIG-GUID: ubOkiGaYQJ0yYY5tm4z6xPQ7kt2_Dvnn X-Authority-Analysis: v=2.4 cv=PbLPQChd c=1 sm=1 tr=0 ts=6a45b7da cx=c_pps a=vVfyC5vLCtgYJKYeQD43oA==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=yx91gb_oNiZeI1HMLzn7:22 a=2XoT9cGsJh1acgpUKzsA:9 a=QEXdDO2ut3YA:10 a=rl5im9kqc5Lf4LNbBjHf:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-07-01_05,2026-06-26_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 clxscore=1015 impostorscore=0 spamscore=0 lowpriorityscore=0 suspectscore=0 phishscore=0 malwarescore=0 adultscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607020007 Hi Leo, On 7/2/2026 12:23 AM, Leo Yan wrote: > On Wed, Jul 01, 2026 at 02:05:02PM +0800, Jie Gan wrote: > >> After probe, pm_runtime_put() allows the device to suspend and the >> runtime suspend callback disables the same clocks. During remove the >> device is left runtime suspended, so pm_runtime_disable() freezes it >> with the clocks already disabled. The devm cleanup that runs afterwards >> calls clk_disable_unprepare() a second time, underflowing the clock >> enable refcount. > > Thanks for fixing the issue. > > The problem is that if the device has already been runtime suspended and > its clock has been disabled, afterwards when remove the device, the devm > cleanup disables the clock again, resulting in clock count underflow. > >> diff --git a/drivers/hwtracing/coresight/coresight-funnel.c b/drivers/hwtracing/coresight/coresight-funnel.c >> index 0abc11f0690c..4c5b94640e6a 100644 >> --- a/drivers/hwtracing/coresight/coresight-funnel.c >> +++ b/drivers/hwtracing/coresight/coresight-funnel.c >> @@ -334,6 +334,7 @@ static void funnel_platform_remove(struct platform_device *pdev) >> return; >> >> funnel_remove(&pdev->dev); >> + pm_runtime_get_sync(&pdev->dev); >> pm_runtime_disable(&pdev->dev); > > Let's use the funnel driver for the discussion. Once we agree on the > approach, we can apply the same change to the other CoreSight platform > drivers. > > How about the following teardown? > > static void funnel_platform_remove(struct platform_device *pdev) > { > struct funnel_drvdata *drvdata = dev_get_drvdata(&pdev->dev); > + int ret; > > if (WARN_ON(!drvdata)) > return; > > + ret = pm_runtime_get_sync(&pdev->dev); > + if (ret < 0) > + dev_warn(&pdev->dev, "failed to resume before remove: %d\n", ret); > + > funnel_remove(&pdev->dev); > + > pm_runtime_disable(&pdev->dev); > + pm_runtime_set_suspended(&pdev->dev); > + pm_runtime_put_noidle(&pdev->dev); > } This proposal looks good to me. I forgot to add pm_runtime_put_noidle to drop the useless reference which created by pm_runtime_get_sync. Thanks, Jie > > The idea is to first resume the device with pm_runtime_get_sync(), then > perform the remove (which is safe if they need to access or clean up > hardware state), and finally clean up the runtime PM states. I mainly > referred to drivers/iio/adc/stm32-adc.c. > > Thanks, > Leo