linux-kernel - [PATCH v2 23/28] coresight: Control path during CPU idle

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Message-Id: <20250701-arm_cs_pm_fix_v3-v2-23-23ebb864fcc1@arm.com>
Date: Tue, 01 Jul 2025 15:53:48 +0100
From: Leo Yan <leo.yan@....com>
To: Suzuki K Poulose <suzuki.poulose@....com>, 
 Mike Leach <mike.leach@...aro.org>, James Clark <james.clark@...aro.org>, 
 Levi Yun <yeoreum.yun@....com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
 Yabin Cui <yabinc@...gle.com>, Keita Morisaki <keyz@...gle.com>, 
 Yuanfang Zhang <quic_yuanfang@...cinc.com>
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, Leo Yan <leo.yan@....com>
Subject: [PATCH v2 23/28] coresight: Control path during CPU idle

Control links and helpers on an activated path during CPU idle. Since
coresight_disable_path_from() does not handle a source device's
helpers, explicitly disable them alongside the source device.

Signed-off-by: Leo Yan <leo.yan@....com>
---
 drivers/hwtracing/coresight/coresight-core.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
index b1c122d1c4164e3ca6f1aaad0bd24917032626be..7693a0eade1a8de6d0960d66f6de682b5d5aff17 100644
--- a/drivers/hwtracing/coresight/coresight-core.c
+++ b/drivers/hwtracing/coresight/coresight-core.c
@@ -458,8 +458,15 @@ static bool coresight_need_save_restore_source(struct coresight_device *csdev)
 
 static int coresight_save_source(struct coresight_device *csdev)
 {
-	if (csdev && source_ops(csdev)->save)
-		return source_ops(csdev)->save(csdev);
+	int ret;
+
+	if (csdev && source_ops(csdev)->save) {
+		ret = source_ops(csdev)->save(csdev);
+		if (ret)
+			return ret;
+
+		coresight_disable_helpers(csdev, NULL);
+	}
 
 	/* Return success if callback is not supported */
 	return 0;
@@ -1662,17 +1669,33 @@ static int coresight_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
 {
 	unsigned int cpu = smp_processor_id();
 	struct coresight_device *source = per_cpu(csdev_source, cpu);
+	struct coresight_path *path;
 
 	if (!coresight_need_save_restore_source(source))
 		return NOTIFY_OK;
 
+	/*
+	 * When run at here, the source device mode is enabled.
+	 * The activated path pointer must not be NULL.
+	 */
+	path = per_cpu(csdev_cpu_path, source->cpu);
+	if (WARN_ON(!path))
+		return NOTIFY_BAD;
+
 	switch (cmd) {
 	case CPU_PM_ENTER:
 		if (coresight_save_source(source))
 			return NOTIFY_BAD;
+
+		coresight_disable_path_from(path, NULL, true);
 		break;
 	case CPU_PM_EXIT:
 	case CPU_PM_ENTER_FAILED:
+		if (_coresight_enable_path(path,
+					   coresight_get_mode(source),
+					   NULL, true))
+			return NOTIFY_BAD;
+
 		coresight_restore_source(source);
 		break;
 	default:

-- 
2.34.1