Hi Linu,
On Tue, Aug 11, 2020 at 07:58:42AM +0530, Linu Cherian wrote:
Coresight driver assumes sink is common across all the ETMs, and tries to build a path between ETM and the first enabled sink found using bus based search. This breaks sysFS usage on implementations that has multiple per core sinks in enabled state.
For this,
- coresight_find_sink API is updated with an additional flag so that it is able to return an enabled sink
- coresight_get_enabled_sink API is updated to do a connection based search, when a source reference is given.
Signed-off-by: Linu Cherian lcherian@marvell.com
Applies on https://git.linaro.org/kernel/coresight.git/log/?h=next
Changes in V3: Fixed checkpatch issue.
.../hwtracing/coresight/coresight-etm-perf.c | 2 +- drivers/hwtracing/coresight/coresight-priv.h | 5 +- drivers/hwtracing/coresight/coresight.c | 51 +++++++++++++++++-- 3 files changed, 51 insertions(+), 7 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c index 1a3169e69bb1..25041d2654e3 100644 --- a/drivers/hwtracing/coresight/coresight-etm-perf.c +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c @@ -223,7 +223,7 @@ static void *etm_setup_aux(struct perf_event *event, void **pages, id = (u32)event->attr.config2; sink = coresight_get_sink_by_id(id); } else {
sink = coresight_get_enabled_sink(true);
sink = coresight_get_enabled_sink(NULL, true);
It is time for this subsystem to move out of the prehistoric age. Please remove the call to coresight_get_enabled_sink() entirely. In the change log you can write that selecting a sink from sysfs is deprecated when using the perf interface. I will personally refactor the code if someone complains that it broke their user space.
} mask = &event_data->mask; diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index f2dc625ea585..010ed26db340 100644 --- a/drivers/hwtracing/coresight/coresight-priv.h +++ b/drivers/hwtracing/coresight/coresight-priv.h @@ -148,10 +148,13 @@ static inline void coresight_write_reg_pair(void __iomem *addr, u64 val, void coresight_disable_path(struct list_head *path); int coresight_enable_path(struct list_head *path, u32 mode, void *sink_data); struct coresight_device *coresight_get_sink(struct list_head *path); -struct coresight_device *coresight_get_enabled_sink(bool reset); +struct coresight_device * +coresight_get_enabled_sink(struct coresight_device *source, bool reset); struct coresight_device *coresight_get_sink_by_id(u32 id); struct coresight_device * coresight_find_default_sink(struct coresight_device *csdev); +struct coresight_device * +coresight_find_enabled_sink(struct coresight_device *csdev); struct list_head *coresight_build_path(struct coresight_device *csdev, struct coresight_device *sink); void coresight_release_path(struct list_head *path); diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c index e9c90f2de34a..ae69169c58d3 100644 --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -566,6 +566,10 @@ static int coresight_enabled_sink(struct device *dev, const void *data) /**
- coresight_get_enabled_sink - returns the first enabled sink found on the bus
- When a source reference is given, enabled sink is found using connection based
- search.
- @source: Coresight source device reference
- @deactivate: Whether the 'enable_sink' flag should be reset
- When operated from perf the deactivate parameter should be set to 'true'.
@@ -576,10 +580,21 @@ static int coresight_enabled_sink(struct device *dev, const void *data)
- parameter should be set to 'false', hence mandating users to explicitly
- clear the flag.
*/ -struct coresight_device *coresight_get_enabled_sink(bool deactivate) +struct coresight_device * +coresight_get_enabled_sink(struct coresight_device *source, bool deactivate)
This code was written during a time when all sources were able to reach a sink, something that is no longer the case. Starting from a source is the right way to go.
{ struct device *dev = NULL;
- struct coresight_device *sink;
- if (!source)
goto bus_search;
Return NULL if a source was not given.
- sink = coresight_find_enabled_sink(source);
- if (sink && deactivate)
sink->activated = false;- return sink;
You get credits for trying to re-use code but in this case I would like to avoid modifying coresight_find_sink() to keep it as simple as possible. I suggest to copy the for() loop in coresight_find_sink() and stop the search when the first activated sink is found. It will introduce a little bit of code duplication but I think we will gain a lot in maintainability.
+bus_search: dev = bus_find_device(&coresight_bustype, NULL, &deactivate, coresight_enabled_sink);
Get rid of this. You can also get rid of the 'deactivate' parameter since it won't be used anymore.
Let me know if you have questions.
Thanks, Mathieu
@@ -828,6 +843,7 @@ coresight_select_best_sink(struct coresight_device *sink, int *depth,
- @csdev: source / current device to check.
- @depth: [in] search depth of calling dev, [out] depth of found sink.
- @enabled: flag to search only enabled sinks
- This will walk the connection path from a source (ETM) till a suitable
- sink is encountered and return that sink to the original caller.
@@ -839,7 +855,7 @@ coresight_select_best_sink(struct coresight_device *sink, int *depth,
- return best sink found, or NULL if not found at this node or child nodes.
*/ static struct coresight_device * -coresight_find_sink(struct coresight_device *csdev, int *depth) +coresight_find_sink(struct coresight_device *csdev, int *depth, bool enabled) { int i, curr_depth = *depth + 1, found_depth = 0; struct coresight_device *found_sink = NULL; @@ -862,7 +878,8 @@ coresight_find_sink(struct coresight_device *csdev, int *depth) child_dev = csdev->pdata->conns[i].child_dev; if (child_dev)
sink = coresight_find_sink(child_dev, &child_depth);
sink = coresight_find_sink(child_dev, &child_depth,enabled);if (sink) found_sink = coresight_select_best_sink(found_sink, @@ -872,6 +889,10 @@ coresight_find_sink(struct coresight_device *csdev, int *depth) } return_def_sink:
- /* Check if we need to return an enabled sink */
- if (enabled && found_sink)
if (!found_sink->activated)found_sink = NULL;@@ -901,10 +922,30 @@ coresight_find_default_sink(struct coresight_device *csdev) /* look for a default sink if we have not found for this device */ if (!csdev->def_sink)
csdev->def_sink = coresight_find_sink(csdev, &depth);
csdev->def_sink = coresight_find_sink(csdev, &depth, false);} +/**
- coresight_find_enabled_sink: Find the suitable enabled sink
- @csdev: starting source to find a connected sink.
- Walks connections graph looking for a suitable sink to enable for the
- supplied source. Uses CoreSight device subtypes and distance from source
- to select the best sink.
- Used in cases where the CoreSight user (sysfs) has selected a sink.
- */
+struct coresight_device * +coresight_find_enabled_sink(struct coresight_device *csdev) +{
- int depth = 0;
- /* look for the enabled sink */
- return coresight_find_sink(csdev, &depth, true);
+}
static int coresight_remove_sink_ref(struct device *dev, void *data) { struct coresight_device *sink = data; @@ -992,7 +1033,7 @@ int coresight_enable(struct coresight_device *csdev) * Search for a valid sink for this session but don't reset the * "enable_sink" flag in sysFS. Users get to do that explicitly. */
- sink = coresight_get_enabled_sink(false);
- sink = coresight_get_enabled_sink(csdev, false); if (!sink) { ret = -EINVAL; goto out;
-- 2.25.1