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[129.46.96.20]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2b04e58d423sm2564824eec.6.2025.12.18.00.10.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Dec 2025 00:10:51 -0800 (PST) From: Yuanfang Zhang Date: Thu, 18 Dec 2025 00:09:50 -0800 Subject: [PATCH v2 10/12] coresight-tmc: Defer probe when associated CPUs are offline Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20251218-cpu_cluster_component_pm-v2-10-2335a6ae62a0@oss.qualcomm.com> References: <20251218-cpu_cluster_component_pm-v2-0-2335a6ae62a0@oss.qualcomm.com> In-Reply-To: <20251218-cpu_cluster_component_pm-v2-0-2335a6ae62a0@oss.qualcomm.com> To: Suzuki K Poulose , Mike Leach , James Clark , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Mathieu Poirier , Leo Yan , Alexander Shishkin , Bjorn Andersson , Konrad Dybcio Cc: kernel@oss.qualcomm.com, coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, Yuanfang Zhang , maulik.shah@oss.qualcomm.com X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1766045439; l=4877; i=yuanfang.zhang@oss.qualcomm.com; s=20250814; h=from:subject:message-id; bh=IB9YQIjoTl8ZOJK7bPPU9ZsiC7//VeDVaYjoFiQJcPE=; b=UImHFUGLEN5dtzF1iBXsV0IkphcLBAir0d5O1DosY6wiCmPvKT6KcI1es7/TAxBzlwuv7XkaG R94jgxoUDKfDMBnuRFGitFAmzSSyqiGLo7ujkx1OpONeUaniOhZUYMz X-Developer-Key: i=yuanfang.zhang@oss.qualcomm.com; a=ed25519; pk=9oS/FoPW5k0CsqSDDrPlnV+kVIOUaAe0O5pr4M1wHgY= X-Proofpoint-ORIG-GUID: S3ogcM_U6a4OfRO4vgfMaYm5DZL4fKru X-Proofpoint-GUID: S3ogcM_U6a4OfRO4vgfMaYm5DZL4fKru X-Authority-Analysis: v=2.4 cv=f8JFxeyM c=1 sm=1 tr=0 ts=6943b70d cx=c_pps a=oF/VQ+ItUULfLr/lQ2/icg==:117 a=ouPCqIW2jiPt+lZRy3xVPw==:17 a=IkcTkHD0fZMA:10 a=wP3pNCr1ah4A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=EUspDBNiAAAA:8 a=fD5cxDGOUVrWaoTO3WMA:9 a=QEXdDO2ut3YA:10 a=3WC7DwWrALyhR5TkjVHa:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMjE4MDA2NiBTYWx0ZWRfX2Kbr6MZQYl12 4a8Fibl8CH5L+OzS2jmEWoDuG86SMpe5agT8aPFtHm6oOm5qO8dS54ne3o3EbHpd5yzMT4HmhhO 9w2fONhrnP38KAzJVTDwTyMzNXkrbnG62vGAh+YCA3ZsDYLP4TIauP/mhD21varmsBNLS8ToWqp 8K8ll7BGGhDuGsTlkQrGyJdrvC2moi9xkc/09/dFF9hbEfP7NAb/MsFPeLSfUmwTBHVT67LSyFq YLHHXmz+fTgTbkncsaZqFiOBq8l/0I1PnOas3p8S/Dbfdyz7jn3ttQOeRVOLHzmyPIGo9OTnPY3 CsWh42Q2kqa+wjwDcc+LWWCwxtA7DJniazh+2vDKTYYjtWGKmXAQz1DpkYQE+ySS4nYmbK3IUt+ aAVqfDCj+uWnAUIifYENjEMHL0KgFQ== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-12-18_01,2025-12-17_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 adultscore=0 clxscore=1015 suspectscore=0 phishscore=0 impostorscore=0 bulkscore=0 malwarescore=0 priorityscore=1501 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2510240001 definitions=main-2512180066 On some platforms, the TMC driver may probe before the associated CPUs are online. This prevents the driver from securely accessing the hardware or configuring it via smp_call_function_single(), which requires the target CPU to be available. To address this, defer the hardware initialization if the associated CPUs are offline: 1. Track such deferred devices in a global list. 2. Register a CPU hotplug callback (`tmc_online_cpu`) to detect when a relevant CPU comes online. 3. Upon CPU online, retry the hardware initialization and registration for the waiting TMC devices. Signed-off-by: Yuanfang Zhang --- drivers/hwtracing/coresight/coresight-tmc-core.c | 59 ++++++++++++++++++++= +++- drivers/hwtracing/coresight/coresight-tmc.h | 4 ++ 2 files changed, 61 insertions(+), 2 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwt= racing/coresight/coresight-tmc-core.c index 5b9f2e57c78f42f0f1460d8a8dcbac72b5f6085e..9182fa8e4074a7c9739494b2f5d= 59be2e96f1d3d 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-core.c +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c @@ -36,6 +36,9 @@ DEFINE_CORESIGHT_DEVLIST(etb_devs, "tmc_etb"); DEFINE_CORESIGHT_DEVLIST(etf_devs, "tmc_etf"); DEFINE_CORESIGHT_DEVLIST(etr_devs, "tmc_etr"); +static LIST_HEAD(tmc_delay_probe); +static enum cpuhp_state hp_online; +static DEFINE_SPINLOCK(delay_lock); =20 int tmc_wait_for_tmcready(struct tmc_drvdata *drvdata) { @@ -1027,6 +1030,8 @@ static int __tmc_probe(struct device *dev, struct res= ource *res) if (!drvdata->supported_cpus) return -EINVAL; =20 + drvdata->dev =3D dev; + cpus_read_lock(); for_each_cpu(cpu, drvdata->supported_cpus) { ret =3D smp_call_function_single(cpu, @@ -1034,11 +1039,16 @@ static int __tmc_probe(struct device *dev, struct r= esource *res) if (!ret) break; } - cpus_read_unlock(); + if (ret) { + scoped_guard(spinlock, &delay_lock) + list_add(&drvdata->link, &tmc_delay_probe); + cpus_read_unlock(); ret =3D 0; goto out; } + + cpus_read_unlock(); } else { tmc_init_hw_config(drvdata); } @@ -1103,8 +1113,12 @@ static void __tmc_remove(struct device *dev) misc_deregister(&drvdata->miscdev); if (drvdata->crashdev.fops) misc_deregister(&drvdata->crashdev); - if (drvdata->csdev) + if (drvdata->csdev) { coresight_unregister(drvdata->csdev); + } else { + scoped_guard(spinlock, &delay_lock) + list_del(&drvdata->link); + } } =20 static void tmc_remove(struct amba_device *adev) @@ -1215,14 +1229,55 @@ static struct platform_driver tmc_platform_driver = =3D { }, }; =20 +static int tmc_online_cpu(unsigned int cpu) +{ + struct tmc_drvdata *drvdata, *tmp; + int ret; + + spin_lock(&delay_lock); + list_for_each_entry_safe(drvdata, tmp, &tmc_delay_probe, link) { + if (cpumask_test_cpu(cpu, drvdata->supported_cpus)) { + list_del(&drvdata->link); + + spin_unlock(&delay_lock); + ret =3D pm_runtime_resume_and_get(drvdata->dev); + if (ret < 0) + return 0; + + tmc_init_hw_config(drvdata); + tmc_clear_self_claim_tag(drvdata); + tmc_add_coresight_dev(drvdata->dev); + pm_runtime_put(drvdata->dev); + spin_lock(&delay_lock); + } + } + spin_unlock(&delay_lock); + return 0; +} + static int __init tmc_init(void) { + int ret; + + ret =3D cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, + "arm/coresight-tmc:online", + tmc_online_cpu, NULL); + + if (ret > 0) + hp_online =3D ret; + else + return ret; + return coresight_init_driver("tmc", &tmc_driver, &tmc_platform_driver, TH= IS_MODULE); } =20 static void __exit tmc_exit(void) { coresight_remove_driver(&tmc_driver, &tmc_platform_driver); + if (hp_online) { + cpuhp_remove_state_nocalls(hp_online); + hp_online =3D 0; + } } module_init(tmc_init); module_exit(tmc_exit); diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracin= g/coresight/coresight-tmc.h index b104b7bf82d2a7a99382636e41d3718cf258d820..2583bc4f556195cd814e674dc66= f08909dea61b2 100644 --- a/drivers/hwtracing/coresight/coresight-tmc.h +++ b/drivers/hwtracing/coresight/coresight-tmc.h @@ -246,6 +246,8 @@ struct tmc_resrv_buf { * @supported_cpus: Represent the CPUs related to this TMC. * @devid: TMC variant ID inferred from the device configuration register. * @desc_name: Name to be used while creating crash interface. + * @dev: pointer to the device associated with this TMC. + * @link: link to the delay_probed list. */ struct tmc_drvdata { struct clk *atclk; @@ -279,6 +281,8 @@ struct tmc_drvdata { struct cpumask *supported_cpus; u32 devid; const char *desc_name; + struct device *dev; + struct list_head link; }; =20 struct etr_buf_operations { --=20 2.34.1