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 <quic_jinlmao@xxxxxxxxxxx>
---
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
