On Fri, May 01, 2020 at 03:02:22PM +0100, Mike Leach wrote:
Adds a method to select a suitable sink connected to a given source.
In cases where no sink is defined, the coresight_find_default_sink routine can search from a given source, through the child connections until a suitable sink is found.
The suitability is defined in a sink_select_priority parameter on the CoreSight device.
This allows for default sink to be discovered were none is specified (e.g. perf command line)
Signed-off-by: Mike Leach mike.leach@linaro.org
drivers/hwtracing/coresight/coresight-priv.h | 2 + drivers/hwtracing/coresight/coresight.c | 76 ++++++++++++++++++++ include/linux/coresight.h | 10 ++- 3 files changed, 87 insertions(+), 1 deletion(-)
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index 890f9a5c97c6..856d8a29658c 100644 --- a/drivers/hwtracing/coresight/coresight-priv.h +++ b/drivers/hwtracing/coresight/coresight-priv.h @@ -150,6 +150,8 @@ 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_sink_by_id(u32 id); +struct coresight_device * +coresight_find_default_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 c71553c09f8e..0564d26f5eb3 100644 --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -769,6 +769,82 @@ void coresight_release_path(struct list_head *path) path = NULL; } +/**
- coresight_find_sink - recursive function to walk trace connections from
- source to find a suitable default sink.
- @csdev: source / current device to check.
- @first_sink: the first lower priority sink found.
- Sinks are given priority weighting, the first HI priority sink will be
- used, if not found then the next highest priority sink will be recorded
- for possible later use.
- (Higher numbers indicate lower priorities, 0 not a sink or not to be
- selected as default)
I think we should go for higher number == higher priority because 1) it is more intuitive and 2) it allows us to grow with minimal changes. Right now ETB10, TMC-ETF and TPIU are '0' and ETR is '1'. If new IP comes out we can assign them higher numbers with little changes.
- This will walk the connection path from a source (etm) till a suitable
- sink is encountered and return that sink to the original caller.
- return HI priority sink, or NULL if not found.
- Best lower priority sink returned in first_sink.
- */
+static struct coresight_device * +coresight_find_sink(struct coresight_device *csdev,
struct coresight_device **first_sink)+{
- int i;
- /* return if highest priority sink */
- if (csdev->sink_select_priority == CORESIGHT_SINK_SELECT_PRIORITY_HI)
return csdev;- /* record if lower priority sink */
- if (csdev->sink_select_priority > CORESIGHT_SINK_SELECT_PRIORITY_HI) {
if ((*first_sink == NULL) ||((*first_sink)->sink_select_priority >csdev->sink_select_priority)) {*first_sink = csdev;}- }
- /*
* Not a sink we want - recursively explore each port found on* this element.*/- for (i = 0; i < csdev->pdata->nr_outport; i++) {
struct coresight_device *child_dev, *sink;child_dev = csdev->pdata->conns[i].child_dev;if (child_dev) {sink = coresight_find_sink(child_dev, first_sink);if (sink)return sink;
If @csdev is a replicator and a sink is found on port '0' components connected, directly or not, to port '1' won't be searched. Also, instead of contending with a 'sink' and a 'first_sink' I would simply make coresight_find_sink() return the highest priority sink found from any @csdev port. That should simplify thing a little.
}- }
- return NULL;
+}
+/**
- coresight_find_default_sink: Find a sink suitable for use as a
- default sink.
- @csdev: starting source to find a connected sink.
- Walks connections graph looking for a suitable sink to enable for the
- supplied source. Uses sink_select_priority values.
- Used in cases where the CoreSight user (perf / sysfs) has not selected a
- sink.
- */
+struct coresight_device * +coresight_find_default_sink(struct coresight_device *csdev) +{
- struct coresight_device *first_sink = NULL, *sink;
- sink = coresight_find_sink(csdev, &first_sink);
- return sink ? sink : first_sink;
+}
/** coresight_validate_source - make sure a source has the right credentials
- @csdev: the device structure for a source.
- @function: the function this was called from.
diff --git a/include/linux/coresight.h b/include/linux/coresight.h index 193cc9dbf448..ff443761c8fc 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -161,10 +161,13 @@ struct coresight_connection {
- @enable: 'true' if component is currently part of an active path.
- @activated: 'true' only if a _sink_ has been activated. A sink can be
activated but not yet enabled. Enabling for a _sink_
appens when a source has been selected for that it.
happens when a source has been selected for that it.
This is obviously wrong, so much I can't even figure out what I meant. Please remove the entire sentence in a cleanup patch that goes at the beginning of this set.
- @ea: Device attribute for sink representation under PMU directory.
- @ect_dev: Associated cross trigger device. Not part of the trace data
path or connections.
- @sink_select_priority: Used when the system is required to choose a default
sink. Higher numbers indicate lower priority. Unused (0) if not*/
a sink / or sink not supported as a default.struct coresight_device { struct coresight_platform_data *pdata; @@ -180,8 +183,13 @@ struct coresight_device { struct dev_ext_attribute *ea; /* cross trigger handling */ struct coresight_device *ect_dev;
- /* mark priority when system choosing a default sink */
- int sink_select_priority;
When I first looked at this set I didn't think there was a need for something like this but after reflection we do since information about the kind of sink (ETB10, TMC-ETF/ETR, TPIU) isn't available from the coresight_device. You can also forget my comment about things not working for ETB10 and TPIU, it is clearer now.
I would simply call this "priority" and move it in the sink section, i.e just under @activated. For extra credit please move @ea after @ops (also in a prequel patch) since it is used for all coresight_device.
}; +/* The highest priority sink - will terminate default sink search */ +#define CORESIGHT_SINK_SELECT_PRIORITY_HI 1
Why not calling this CORESIGHT_PRIORITY_ETR, so that when the next best thing comes out we can have CORESIGHT_PRIORITY_NEXT_BEST_THING. Hopefully we won't need to do that because everyone will move to 1:1 topologies but I know better.
For you next revision, please rebase on coresight-next, I couldn't apply this one properly.
Thanks, Mathieu
/*
- coresight_dev_list - Mapping for devices to "name" index for device
- names.
-- 2.17.1