linux-kernel - [RFC PATCH 01/14] coresight: etm4x: Skip save/restore before device registration

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Date:   Wed, 22 Jul 2020 18:20:27 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, mike.leach@...aro.org,
        mathieu.poirier@...aro.org, coresight@...ts.linaro.org,
        Suzuki K Poulose <suzuki.poulose@....com>
Subject: [RFC PATCH 01/14] coresight: etm4x: Skip save/restore before device registration

Skip cpu save/restore before the coresight device is registered.

Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Mike Leach <mike.leach@...aro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 drivers/hwtracing/coresight/coresight-etm4x.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
index 6d7d2169bfb2..cb83fb77ded6 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -1135,7 +1135,13 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
 {
 	int i, ret = 0;
 	struct etmv4_save_state *state;
-	struct device *etm_dev = &drvdata->csdev->dev;
+	struct coresight_device *csdev = drvdata->csdev;
+	struct device *etm_dev;
+
+	if (WARN_ON(!csdev))
+		return -ENODEV;
+
+	etm_dev = &csdev->dev;
 
 	/*
 	 * As recommended by 3.4.1 ("The procedure when powering down the PE")
@@ -1261,6 +1267,10 @@ static void etm4_cpu_restore(struct etmv4_drvdata *drvdata)
 {
 	int i;
 	struct etmv4_save_state *state = drvdata->save_state;
+	struct coresight_device *csdev = drvdata->csdev;
+
+	if (WARN_ON(!csdev))
+		return;
 
 	CS_UNLOCK(drvdata->base);
 
@@ -1368,6 +1378,10 @@ static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd,
 
 	drvdata = etmdrvdata[cpu];
 
+	/* If we have not registered the device there is nothing to do */
+	if (!drvdata->csdev)
+		return NOTIFY_OK;
+
 	if (!drvdata->save_state)
 		return NOTIFY_OK;
 
-- 
2.24.1