The coresight_disable_source_sysfs function should verify the
mode of the coresight device before disabling the source.
However, the mode for the dummy source device is always set to
CS_MODE_DISABLED, resulting in the check consistently failing.
As a result, dummy source cannot be properly disabled.

Configure CS_MODE_SYSFS/CS_MODE_PERF during the enablement.
Configure CS_MODE_DISABLED during the disablement.

Fixes: 9d3ba0b6c056 ("Coresight: Add coresight dummy driver")
Signed-off-by: Jie Gan <quic_jiegan@quicinc.com>
---
 drivers/hwtracing/coresight/coresight-dummy.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-dummy.c b/drivers/hwtracing/coresight/coresight-dummy.c
index ac70c0b491be..dab389a5507c 100644
--- a/drivers/hwtracing/coresight/coresight-dummy.c
+++ b/drivers/hwtracing/coresight/coresight-dummy.c
@@ -23,6 +23,9 @@ DEFINE_CORESIGHT_DEVLIST(sink_devs, "dummy_sink");
 static int dummy_source_enable(struct coresight_device *csdev,
 			       struct perf_event *event, enum cs_mode mode)
 {
+	if (!coresight_take_mode(csdev, mode))
+		return -EBUSY;
+
 	dev_dbg(csdev->dev.parent, "Dummy source enabled\n");
 
 	return 0;
@@ -31,6 +34,7 @@ static int dummy_source_enable(struct coresight_device *csdev,
 static void dummy_source_disable(struct coresight_device *csdev,
 				 struct perf_event *event)
 {
+	coresight_set_mode(csdev, CS_MODE_DISABLED);
 	dev_dbg(csdev->dev.parent, "Dummy source disabled\n");
 }
 
-- 
2.34.1

On 26/06/2024 06:05, Jie Gan wrote:
> The coresight_disable_source_sysfs function should verify the
> mode of the coresight device before disabling the source.
> However, the mode for the dummy source device is always set to
> CS_MODE_DISABLED, resulting in the check consistently failing.
> As a result, dummy source cannot be properly disabled.
> 
> Configure CS_MODE_SYSFS/CS_MODE_PERF during the enablement.
> Configure CS_MODE_DISABLED during the disablement.

30 email addresses in CC, 90% of them not related to the patch. Sorry,
this is way too much spamming. Do not Cc unrelated people. Do not Cc me
on such stuff.

<form letter>
Please use scripts/get_maintainers.pl to get a list of necessary people
and lists to CC (and consider --no-git-fallback argument). It might
happen, that command when run on an older kernel, gives you outdated
entries. Therefore please be sure you base your patches on recent Linux
kernel.

Tools like b4 or scripts/get_maintainer.pl provide you proper list of
people, so fix your workflow. Tools might also fail if you work on some
ancient tree (don't, instead use mainline) or work on fork of kernel
(don't, instead use mainline). Just use b4 and everything should be
fine, although remember about `b4 prep --auto-to-cc` if you added new
patches to the patchset.
</form letter>

Best regards,
Krzysztof