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.
Signed-off-by: Mao Jinlong <[email protected]>
---
drivers/hwtracing/coresight/coresight-cti-sysfs.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
index 6d59c815ecf5..b1ed424ae043 100644
--- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
@@ -108,10 +108,17 @@ 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);
+ pm_runtime_put(dev->parent);
+ }
if (ret)
return ret;
return size;
--
2.17.1
On 24/12/2022 14:17, Mao Jinlong wrote:
> 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.
>
> Signed-off-by: Mao Jinlong <[email protected]>
> ---
> drivers/hwtracing/coresight/coresight-cti-sysfs.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> index 6d59c815ecf5..b1ed424ae043 100644
> --- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> @@ -108,10 +108,17 @@ 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);
> + pm_runtime_put(dev->parent);
Hi Jinlong,
This new pm_runtime_put() causes this when writing 0 to enable:
[ 483.253814] coresight-cti 23020000.cti: Runtime PM usage count
underflow!
Maybe we can modify cti_disable_hw() to return a value to indicate that
the disable actually happened, and only then call pm_runtime_put().
I suppose you could also check in the store function if it was already
enabled first, but then I don't know what kind of locking that would
need? cti_disable_hw() already seems to have a couple of locks, so maybe
the return value solution is easiest.
Thanks
James
On 04/01/2023 13:11, James Clark wrote:
>
>
> On 24/12/2022 14:17, Mao Jinlong wrote:
>> 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.
>>
>> Signed-off-by: Mao Jinlong <[email protected]>
>> ---
>> drivers/hwtracing/coresight/coresight-cti-sysfs.c | 11 +++++++++--
>> 1 file changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
>> index 6d59c815ecf5..b1ed424ae043 100644
>> --- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c
>> +++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
>> @@ -108,10 +108,17 @@ 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);
>> + pm_runtime_put(dev->parent);
>
> Hi Jinlong,
>
> This new pm_runtime_put() causes this when writing 0 to enable:
>
> [ 483.253814] coresight-cti 23020000.cti: Runtime PM usage count
> underflow!
>
> Maybe we can modify cti_disable_hw() to return a value to indicate that
> the disable actually happened, and only then call pm_runtime_put().
>
> I suppose you could also check in the store function if it was already
> enabled first, but then I don't know what kind of locking that would
> need? cti_disable_hw() already seems to have a couple of locks, so maybe
> the return value solution is easiest.
>
We've also just seen another issue where multiple calls to
cti_disable_hw() can cause enable_req_count to go negative. I'm going to
work on a few fixes (including yours) to make sure that it's complete
and post it shortly.
James
On 1/5/2023 9:55 PM, James Clark wrote:
>
> On 04/01/2023 13:11, James Clark wrote:
>>
>> On 24/12/2022 14:17, Mao Jinlong wrote:
>>> 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.
>>>
>>> Signed-off-by: Mao Jinlong <[email protected]>
>>> ---
>>> drivers/hwtracing/coresight/coresight-cti-sysfs.c | 11 +++++++++--
>>> 1 file changed, 9 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
>>> index 6d59c815ecf5..b1ed424ae043 100644
>>> --- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c
>>> +++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
>>> @@ -108,10 +108,17 @@ 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);
>>> + pm_runtime_put(dev->parent);
>> Hi Jinlong,
>>
>> This new pm_runtime_put() causes this when writing 0 to enable:
>>
>> [ 483.253814] coresight-cti 23020000.cti: Runtime PM usage count
>> underflow!
>>
>> Maybe we can modify cti_disable_hw() to return a value to indicate that
>> the disable actually happened, and only then call pm_runtime_put().
>>
>> I suppose you could also check in the store function if it was already
>> enabled first, but then I don't know what kind of locking that would
>> need? cti_disable_hw() already seems to have a couple of locks, so maybe
>> the return value solution is easiest.
>>
> We've also just seen another issue where multiple calls to
> cti_disable_hw() can cause enable_req_count to go negative. I'm going to
> work on a few fixes (including yours) to make sure that it's complete
> and post it shortly.
Ok, Thank you, James.
>
> James