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(h-178-174-189-39.A498.priv.bahnhof.se. [178.174.189.39]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c296608480esm468632666b.36.2026.09.14.08.01.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Sep 2026 08:01:57 -0700 (PDT) From: Ulf Hansson To: Sudeep Holla , "Rafael J . Wysocki" , Daniel Lezcano , linux-pm@vger.kernel.org Cc: Dhruva Gole , Abel Vesa , Lorenzo Pieralisi , Christian Loehle , Maulik Shah , Yuanfang Zhang , Sneh Mankad , Suzuki K Poulose , Ulf Hansson , linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 2/5] pmdomain: core: Allow a non-CPU device in a CPU PM domain to do power on Date: Mon, 14 Sep 2026 17:01:38 +0200 Message-ID: <20260914150146.187622-3-ulf.hansson@oss.qualcomm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260914150146.187622-1-ulf.hansson@oss.qualcomm.com> References: <20260914150146.187622-1-ulf.hansson@oss.qualcomm.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTE0MDIxNSBTYWx0ZWRfXyDDBIcXubzML eBwaBRfgWHfUiKejqwPbQdXSUhhBwFgxajoD+jOFKtzcg61hxctTwZfpqyqcuUA3i2QrjqfPyGA NemzfbJ0Q1I+iqeKHmwCDH/LgqLy/iQYi9dJBWE4FJwolL487FqAEYjEnuyXsZYXNHbEix7286V bMThJx8RDMCfAY9Z8Y0UtoEV4I5fUB/x779K8ZCeUJfg9ALV0NOTGTeN6i+SGwo0l3QUoZquvZg sn5qXpUJLy8qewTWWjCUWTcEy/lPrLw1wTos2//Re249iEd8WARW1Fe562REvzBpNsSUB0i3T0d CyAQ/SSJacQd9dyRSI1Cwpt7mIk/QMvE3WH9U4xu6FVLehHU5fHXDcnlVmGL7GPiQv3YgrvCIBC mCQayUNDrgLPLWQV46sd76BkIXBt1+7pkyU0NChV6lwE5SPa11y6qAdAVKDKMZCnUdGditqpOIQ NtO0x4l4E3haa9Kr89Q== X-Proofpoint-GUID: 3yLJ8rBReKE2dn4dgLH_GslxPAuXjKs_ X-Proofpoint-Spam-Info: AW1haW4tMjYwOTE0MDIxNSBTYWx0ZWRfX5qgK2E7qlWwz IcKdYnsv750C+mV+PTTlbzpTS5fgpHVWi6p6SabhfPUKwAbJ/PlpmjgxlpW0YfpD5vQClS/q5KC sWyEe8Wtd/TMvY0/VO8mbUj6hOxgeRI= X-Proofpoint-ORIG-GUID: 3yLJ8rBReKE2dn4dgLH_GslxPAuXjKs_ X-Authority-Analysis: v=2.4 cv=MsrHeGae c=1 sm=1 tr=0 ts=6aa80c69 cx=c_pps a=lkkFf9KBb43tY3aOjL++dA==:117 a=h7aNHqOhPKB91FvYUefsSA==:17 a=u8BtVuMVLpZXKRMe:21 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=eoimf2acIAo5FJnRuUoq:22 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=EUspDBNiAAAA:8 a=CAA96EveQzfqUpAuUaoA:9 a=k4UEASGLJojhI9HsvVT1:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-14_03,2026-09-14_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 malwarescore=0 suspectscore=0 clxscore=1015 adultscore=0 impostorscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609140215 A driver for a non-CPU device that is attached to a CPU PM domain (the genpd has the GENPD_FLAG_CPU_DOMAIN configuration set), is currently not able to power on the PM domain. More precisely, to power on a CPU PM domain one of its corresponding CPUs needs to be woken up if they are idle. The current support for a non-CPU device is that its driver can only prevent an already powered on CPU PM domain from being powered off. This leads to problems for a driver while probing its device or when it needs to call pm_runtime_get_sync() to turn on the power for it. From the driver point of view it looks like it all works fine, but when accessing the device it may end up with various errors as the device may not be fully powered on. To fix the behavior for these types of devices, let's adjust the behaviour in genpd_power_on() to wake up an idle CPU that belongs to it, in cases when it's needed. Link: https://lore.kernel.org/all/CAPx+jO-sCierYj8jnoKQHckJG16dOBxnNrsZVYO=38R2cLV8nw@mail.gmail.com/ Reviewed-by: Abel Vesa Tested-by: Yuanfang Zhang Reviewed-by: Dhruva Gole Signed-off-by: Ulf Hansson --- Changes in v4: - Decreased the timeout. Changes in v3: - Moved to atomic polling, pointed out by Dhruva. Changes in v2: - Rename a function according to Abel's suggestion. --- drivers/pmdomain/core.c | 80 ++++++++++++++++++++++++++++++++++++++--- 1 file changed, 75 insertions(+), 5 deletions(-) diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c index 6abe8b198949..c593a3479ad0 100644 --- a/drivers/pmdomain/core.c +++ b/drivers/pmdomain/core.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -19,11 +20,14 @@ #include #include #include +#include #include #include #include #include +#include + /* Provides a unique ID for each genpd device */ static DEFINE_IDA(genpd_ida); @@ -32,7 +36,9 @@ static const struct bus_type genpd_provider_bus_type = { .name = "genpd_provider", }; -#define GENPD_RETRY_MAX_MS 250 /* Approximate */ +#define GENPD_RETRY_MAX_MS 250 /* Approximate */ +#define GENPD_CPU_ON_POLL_PERIOD_US 100 /* 100us */ +#define GENPD_CPU_ON_TIMEOUT_US 300000 /* 300ms */ #define GENPD_DEV_CALLBACK(genpd, type, callback, dev) \ ({ \ @@ -1026,15 +1032,75 @@ static void genpd_power_off(struct generic_pm_domain *genpd, bool one_dev_on, } } +static bool genpd_status_on(struct generic_pm_domain *genpd) +{ + bool is_on; + + genpd_lock(genpd); + is_on = genpd_status_on_unlocked(genpd); + genpd_unlock(genpd); + + return is_on; +} + +static int genpd_wakeup_cpu(struct generic_pm_domain *genpd) +{ + unsigned int cpu; + bool is_on; + int ret; + + /* Find the first online CPU in the genpd's cpumask. */ + cpu = cpumask_first_and(genpd->cpus, cpu_online_mask); + if (cpu >= nr_cpu_ids) + return -EAGAIN; + + genpd_unlock(genpd); + + /* Send a IPI to wakeup the selected CPU. */ + smp_send_reschedule(cpu); + + /* Poll to wait for it to complete the power on sequence. */ + ret = readx_poll_timeout_atomic(genpd_status_on, genpd, is_on, is_on, + GENPD_CPU_ON_POLL_PERIOD_US, + GENPD_CPU_ON_TIMEOUT_US); + + genpd_lock(genpd); + + /* Re-check the status as we have released the lock in between. */ + if (ret || !genpd_status_on_unlocked(genpd)) + return -EAGAIN; + + return 0; +} + +static bool genpd_need_alive_cpu(struct generic_pm_domain *genpd, + struct device *dev) +{ + if (!genpd_is_cpu_domain(genpd)) + return false; + + /* This is not for CPU devices as those are managed differently. */ + if (to_gpd_data(dev->power.subsys_data->domain_data)->cpu >= 0) + return false; + + /* + * If the current CPU doesn't belong to the genpd's cpumask, we need to + * wake up one of those idle CPUs to power on the CPU domain correctly. + */ + return !cpumask_test_cpu(smp_processor_id(), genpd->cpus); +} + /** * genpd_power_on - Restore power to a given PM domain and its parents. * @genpd: PM domain to power up. + * @dev: The device that needs the PM domain to power on. * @depth: nesting count for lockdep. * * Restore power to @genpd and all of its parents so that it is possible to * resume a device belonging to it. */ -static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth) +static int genpd_power_on(struct generic_pm_domain *genpd, struct device *dev, + unsigned int depth) { struct gpd_link *link; int ret = 0; @@ -1042,6 +1108,10 @@ static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth) if (genpd_status_on_unlocked(genpd)) return 0; + /* Special case for a device attached to a CPU domain. */ + if (genpd_need_alive_cpu(genpd, dev)) + return genpd_wakeup_cpu(genpd); + /* Reflect over the entered idle-states residency for debugfs. */ genpd_reflect_residency(genpd); @@ -1056,7 +1126,7 @@ static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth) genpd_sd_counter_inc(parent); genpd_lock_nested(parent, depth + 1); - ret = genpd_power_on(parent, depth + 1); + ret = genpd_power_on(parent, dev, depth + 1); genpd_unlock(parent); if (ret) { @@ -1306,7 +1376,7 @@ static int genpd_runtime_resume(struct device *dev) genpd_lock(genpd); genpd_restore_performance_state(dev, gpd_data->rpm_pstate); - ret = genpd_power_on(genpd, 0); + ret = genpd_power_on(genpd, dev, 0); genpd_unlock(genpd); if (ret) @@ -3410,7 +3480,7 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev, if (power_on) { genpd_lock(pd); - ret = genpd_power_on(pd, 0); + ret = genpd_power_on(pd, dev, 0); genpd_unlock(pd); } -- 2.43.0