[PATCH] coresight: add PM runtime calls to coresight_simple_func()

It is mandatory to enable a coresight block's power domain before
trying to access management registers.  Otherwise the transaction
simply stalls, leading to a system hang.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/hwtracing/coresight/coresight-priv.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
index ad975c58080d..b047241e7496 100644
--- a/drivers/hwtracing/coresight/coresight-priv.h
+++ b/drivers/hwtracing/coresight/coresight-priv.h

@@ -16,6 +16,7 @@
 #include <linux/bitops.h>
 #include <linux/io.h>
 #include <linux/coresight.h>
+#include <linux/pm_runtime.h>
 
 /*
  * Coresight management registers (0xf00-0xfcc)

@@ -42,8 +43,10 @@ static ssize_t name##_show(struct device *_dev,				\
 			   struct device_attribute *attr, char *buf)	\
 {									\
 	type *drvdata = dev_get_drvdata(_dev->parent);			\
+	pm_runtime_get_sync(_dev->parent);				\
 	return scnprintf(buf, PAGE_SIZE, "0x%x\n",			\
 			 readl_relaxed(drvdata->base + offset));	\
+	pm_runtime_put_sync(_dev->parent);				\
 }									\
 static DEVICE_ATTR_RO(name)
 

-- 
2.5.0

On 17/06/16 18:41, Mathieu Poirier wrote:

This is wrong, I just noticed when I was playing around this.
Perhaps you meant to do this before returning ? I wonder why compiler
doesn't throw any error.

-- 
Regards,
Sudeep

On 23 June 2016 at 10:37, Sudeep Holla [off-list ref] wrote:

On 17/06/16 18:41, Mathieu Poirier wrote:

quoted

It is mandatory to enable a coresight block's power domain before
trying to access management registers.  Otherwise the transaction
simply stalls, leading to a system hang.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
  drivers/hwtracing/coresight/coresight-priv.h | 3 +++
  1 file changed, 3 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-priv.h

b/drivers/hwtracing/coresight/coresight-priv.h
index ad975c58080d..b047241e7496 100644

--- a/drivers/hwtracing/coresight/coresight-priv.h
+++ b/drivers/hwtracing/coresight/coresight-priv.h

@@ -16,6 +16,7 @@
  #include <linux/bitops.h>
  #include <linux/io.h>
  #include <linux/coresight.h>
+#include <linux/pm_runtime.h>

  /*
   * Coresight management registers (0xf00-0xfcc)

@@ -42,8 +43,10 @@ static ssize_t name##_show(struct device *_dev,

\
                           struct device_attribute *attr, char *buf)    \
  {                                                                     \
        type *drvdata = dev_get_drvdata(_dev->parent);                  \
+       pm_runtime_get_sync(_dev->parent);                              \
        return scnprintf(buf, PAGE_SIZE, "0x%x\n",                      \
                         readl_relaxed(drvdata->base + offset));        \
+       pm_runtime_put_sync(_dev->parent);                              \

This is wrong, I just noticed when I was playing around this.
Perhaps you meant to do this before returning ? I wonder why compiler
doesn't throw any error.

Yes of course - I'll respin.

--
Regards,
Sudeep