linux-kernel - [PATCH 4/6] coresight: etm3x: Deal with CLAIM tag before and after accessing HW

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Message-Id: <1543603387-32645-5-git-send-email-mathieu.poirier@linaro.org>
Date:   Fri, 30 Nov 2018 11:43:05 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     gregkh@...uxfoundation.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 4/6] coresight: etm3x: Deal with CLAIM tag before and after accessing HW

This patch moves access to the CLAIM tag so that no modification to the HW
happens before and after the CLAIM operation has been carried.

Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 drivers/hwtracing/coresight/coresight-etm3x.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x.c
index fd5c4cca7db5..6f30d52da9e4 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x.c
@@ -363,15 +363,16 @@ static int etm_enable_hw(struct etm_drvdata *drvdata)
 
 	CS_UNLOCK(drvdata->base);
 
+	rc = coresight_claim_device_unlocked(drvdata->base);
+	if (rc)
+		goto done;
+
 	/* Turn engine on */
 	etm_clr_pwrdwn(drvdata);
 	/* Apply power to trace registers */
 	etm_set_pwrup(drvdata);
 	/* Make sure all registers are accessible */
 	etm_os_unlock(drvdata);
-	rc = coresight_claim_device_unlocked(drvdata->base);
-	if (rc)
-		goto done;
 
 	etm_set_prog(drvdata);
 
@@ -422,8 +423,6 @@ static int etm_enable_hw(struct etm_drvdata *drvdata)
 	etm_clr_prog(drvdata);
 
 done:
-	if (rc)
-		etm_set_pwrdwn(drvdata);
 	CS_LOCK(drvdata->base);
 
 	dev_dbg(drvdata->dev, "cpu: %d enable smp call done: %d\n",
@@ -577,9 +576,9 @@ static void etm_disable_hw(void *info)
 	for (i = 0; i < drvdata->nr_cntr; i++)
 		config->cntr_val[i] = etm_readl(drvdata, ETMCNTVRn(i));
 
+	etm_set_pwrdwn(drvdata);
 	coresight_disclaim_device_unlocked(drvdata->base);
 
-	etm_set_pwrdwn(drvdata);
 	CS_LOCK(drvdata->base);
 
 	dev_dbg(drvdata->dev, "cpu: %d disable smp call done\n", drvdata->cpu);
-- 
2.7.4