linux-kernel - [PATCH] coresight: tmc: fix for trace collection bug in sysFS mode

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Date:   Tue, 13 Sep 2016 05:20:45 -0700
From:   Venkatesh Vivekanandan <venkatesh.vivekanandan@...adcom.com>
To:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     mathieu.poirier@...aro.org,
        Venkatesh Vivekanandan <venkatesh.vivekanandan@...adcom.com>
Subject: [PATCH] coresight: tmc: fix for trace collection bug in sysFS mode

tmc_etb_dump_hw is never called in sysFS mode to collect trace from
hardware, because drvdata->mode is set to CS_MODE_DISABLED at
tmc_disable_etf/etr_sink

static void tmc_etb_disable_hw(struct tmc_drvdata *drvdata)
{
        .
        .
        if (local_read(&drvdata->mode) == CS_MODE_SYSFS)
                tmc_etb_dump_hw(drvdata);
        .
        .
}

static void tmc_disable_etf_sink(struct coresight_device *csdev)
{
       .
       .
        val = local_xchg(&drvdata->mode, CS_MODE_DISABLED);
        /* Disable the TMC only if it needs to */
        if (val != CS_MODE_DISABLED)
                tmc_etb_disable_hw(drvdata);
       .
       .
}

Signed-off-by: Venkatesh Vivekanandan <venkatesh.vivekanandan@...adcom.com>
---
 drivers/hwtracing/coresight/coresight-tmc-etf.c | 9 +++++----
 drivers/hwtracing/coresight/coresight-tmc-etr.c | 9 +++++----
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index 466af86..c7fb7f7 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -61,6 +61,8 @@ static void tmc_etb_dump_hw(struct tmc_drvdata *drvdata)
 
 static void tmc_etb_disable_hw(struct tmc_drvdata *drvdata)
 {
+	long val;
+
 	CS_UNLOCK(drvdata->base);
 
 	tmc_flush_and_stop(drvdata);
@@ -68,7 +70,8 @@ static void tmc_etb_disable_hw(struct tmc_drvdata *drvdata)
 	 * When operating in sysFS mode the content of the buffer needs to be
 	 * read before the TMC is disabled.
 	 */
-	if (local_read(&drvdata->mode) == CS_MODE_SYSFS)
+	val = local_xchg(&drvdata->mode, CS_MODE_DISABLED);
+	if (val == CS_MODE_SYSFS)
 		tmc_etb_dump_hw(drvdata);
 	tmc_disable_hw(drvdata);
 
@@ -225,7 +228,6 @@ static int tmc_enable_etf_sink(struct coresight_device *csdev, u32 mode)
 
 static void tmc_disable_etf_sink(struct coresight_device *csdev)
 {
-	long val;
 	unsigned long flags;
 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
@@ -235,9 +237,8 @@ static void tmc_disable_etf_sink(struct coresight_device *csdev)
 		return;
 	}
 
-	val = local_xchg(&drvdata->mode, CS_MODE_DISABLED);
 	/* Disable the TMC only if it needs to */
-	if (val != CS_MODE_DISABLED)
+	if (local_read(&drvdata->mode) != CS_MODE_DISABLED)
 		tmc_etb_disable_hw(drvdata);
 
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 688be9e..480794b 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -73,6 +73,8 @@ static void tmc_etr_dump_hw(struct tmc_drvdata *drvdata)
 
 static void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
 {
+	long val;
+
 	CS_UNLOCK(drvdata->base);
 
 	tmc_flush_and_stop(drvdata);
@@ -80,7 +82,8 @@ static void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
 	 * When operating in sysFS mode the content of the buffer needs to be
 	 * read before the TMC is disabled.
 	 */
-	if (local_read(&drvdata->mode) == CS_MODE_SYSFS)
+	val = local_xchg(&drvdata->mode, CS_MODE_DISABLED);
+	if (val == CS_MODE_SYSFS)
 		tmc_etr_dump_hw(drvdata);
 	tmc_disable_hw(drvdata);
 
@@ -215,7 +218,6 @@ static int tmc_enable_etr_sink(struct coresight_device *csdev, u32 mode)
 
 static void tmc_disable_etr_sink(struct coresight_device *csdev)
 {
-	long val;
 	unsigned long flags;
 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
@@ -225,9 +227,8 @@ static void tmc_disable_etr_sink(struct coresight_device *csdev)
 		return;
 	}
 
-	val = local_xchg(&drvdata->mode, CS_MODE_DISABLED);
 	/* Disable the TMC only if it needs to */
-	if (val != CS_MODE_DISABLED)
+	if (local_read(&drvdata->mode) != CS_MODE_DISABLED)
 		tmc_etr_disable_hw(drvdata);
 
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
-- 
2.1.0