linux-kernel - [PATCH v3 2/3] coresight: cti: Add PM runtime call in enable

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Message-Id: <20230110110736.2709917-3-james.clark@arm.com>
Date:   Tue, 10 Jan 2023 11:07:35 +0000
From:   James Clark <james.clark@....com>
To:     coresight@...ts.linaro.org, quic_jinlmao@...cinc.com,
        suzuki.poulose@....com, mike.leach@...aro.org
Cc:     James Clark <james.clark@....com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 2/3] coresight: cti: Add PM runtime call in enable_store

From: Mao Jinlong <quic_jinlmao@...cinc.com>

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.

Fixes: 6746eae4bbad ("coresight: cti: Fix hang in cti_disable_hw()")
Signed-off-by: Mao Jinlong <quic_jinlmao@...cinc.com>
[Change to only call pm_runtime_put if a disable happened]
Tested-by: Jinlong Mao <quic_jinlmao@...cinc.com>
Signed-off-by: James Clark <james.clark@....com>
---
 drivers/hwtracing/coresight/coresight-cti-sysfs.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
index 6d59c815ecf5..71e7a8266bb3 100644
--- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
@@ -108,10 +108,19 @@ 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);
+		if (!ret)
+			pm_runtime_put(dev->parent);
+	}
+
 	if (ret)
 		return ret;
 	return size;
-- 
2.25.1