Re: [PATCH 2/4] coresight: Add support for multiple output ports on the funnel

On 4/8/2024 9:28 PM, Mike Leach wrote:

Hi Tao,

Using a DT label in this way is not how connections should be described in device tree, The association needs to be between the input and output ports of the component not and extra link back to the source.

If your "funnel" has multiple input and output ports, then it is no longer a funnel. As you describe it - the input ports are statically associated with an output port, so the device is effectively a set of individual funnels. Given that the association between the inputs and outputs is known at time of compilation - then these can be inferred from the components compatible string and handled internally during driver probe.

This component should therefore really have its own driver, and not be described as a standard funnel. In this way you can handle the input and output associations within the driver and create a path in the normal way, avoiding the need for large changes to the coresight API. Having a specific driver will allow creation of sets of associated input and output connections.

|----------| |---------| |----------| | TPDM 0 | | Source | | TPDM 1 | |----------| |---------| |----------| | | | | | | | --------- | | | | | | | | | | | -------------/ -------------------- \ Funnel 0 / | ----------- | | | | | | | \ -------------/ \ Funnel 1 / -----------/ | |---------------------| | |------------| | | | | | \ ----------------/ | \ TPDA 0 / | --------------/ | | | | | | -------------------------------/ \ Funnel 2 / ---------------------------

Our current problem is how to build trace path. We have the topology as shown above. TPDM0 and "other source" connect to Funnel0, and Funnel0 and TPDM1 connect to Funnel1. Finally, "other source" trace path is directly connected from Funnel1 to Funnel2. And TPDM0 and TPDM1 need to pass through TPDA0 and then connect to Funnel2. In this case, if we don't label the source in the connection, we can't think of any other way to successfully build the trace path.

Are there any other good approach to our problem?

Best, Tao

Regards

Mike

On Fri, 29 Mar 2024 at 09:27, Tao Zhangquic_taozha@quicinc.com wrote:

...

On 3/22/2024 12:41 AM, Suzuki K Poulose wrote:

...

On 21/03/2024 08:32, Tao Zhang wrote:

...

Funnel devices are now capable of supporting multiple-inputs and multiple-outputs configuration with in built hardware filtering for TPDM devices. Add software support to this function. Output port is selected according to the source in the trace path.

The source of the input port on funnels will be marked in the device tree. e.g. tpdm@xxxxxxx { ... ... ... ... };

funnel_XXX: funnel@xxxxxxx { ... ... ... ... out-ports { ... ... ... ... port@x { ... ... ... ... label = "xxxxxxx.tpdm"; <-- To label the source }; corresponding to the output ... ... ... ... connection "port@x". And this }; is a hardware static connections. ... ... ... ... Here needs to refer to hardware }; design.

Then driver will parse the source label marked in the device tree, and save it to the coresight path. When the function needs to know the source label, it could obtain it from coresight path parameter. Finally, the output port knows which source it corresponds to, and it also knows which input port it corresponds to.

Why do we need labels ? We have connection information for all devices (both in and out), so, why do we need this label to find a device ?

Because our funnel's design has multi-output ports, the data stream will not

know which output port should pass in building the data trace path. This source

label can make the data stream find the right output port to go.

...

And also, I thought TPDM is a source device, why does a funnel output port link to a source ?

No, this label doesn't mean this funnel output port link to a source, it just let

the output port know its data source.

...

Are these funnels programmable ? Or, are they static ? If they are static, do these need to be described in the DT ? If they are simply acting as a "LINK" (or HWFIFO ?)

These funnels are static, and we will add the "label" to the DT to describe the

multi-output ports for these funnels.

"If they are simply acting as a "LINK" (or HWFIFO ?) " I'm not sure what's the meaning

of this. Could you describe it in detail?

Best,

Tao

...

Suzuki

...

Signed-off-by: Tao Zhangquic_taozha@quicinc.com

drivers/hwtracing/coresight/coresight-core.c | 81 ++++++++++++++++--- .../hwtracing/coresight/coresight-platform.c | 5 ++ include/linux/coresight.h | 2 + 3 files changed, 75 insertions(+), 13 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c index 5dde597403b3..b1b5e6d9ec7a 100644 --- a/drivers/hwtracing/coresight/coresight-core.c +++ b/drivers/hwtracing/coresight/coresight-core.c @@ -113,15 +113,63 @@ struct coresight_device *coresight_get_percpu_sink(int cpu) } EXPORT_SYMBOL_GPL(coresight_get_percpu_sink); +static struct coresight_device *coresight_get_source(struct list_head *path) +{

• struct coresight_device *csdev;
• if (!path)

•    return NULL;
  

• csdev = list_first_entry(path, struct coresight_node, link)->csdev;
• if (csdev->type != CORESIGHT_DEV_TYPE_SOURCE)

•    return NULL;
  

• return csdev;

+}

+/**

• • coresight_source_filter - checks whether the connection matches

the source

• • of path if connection is binded to specific source.
• • @path: The list of devices
• • @conn: The connection of one outport
• • Return zero if the connection doesn't have a source binded or

source of the

• • path matches the source binds to connection.
• */

+static int coresight_source_filter(struct list_head *path,

•        struct coresight_connection *conn)
  

+{

• int ret = 0;
• struct coresight_device *source = NULL;
• if (conn->source_label == NULL)

•    return ret;
  

• source = coresight_get_source(path);
• if (source == NULL)

•    return ret;
  

• if (strstr(kobject_get_path(&source->dev.kobj, GFP_KERNEL),

•        conn->source_label))
  

•    ret = 0;
  

• else

•    ret = -1;
  

• return ret;

+}

• static struct coresight_connection * coresight_find_out_connection(struct coresight_device *src_dev,

•              struct coresight_device *dest_dev)
  

•              struct coresight_device *dest_dev,
  

•              struct list_head *path)
  

  { int i; struct coresight_connection *conn; for (i = 0; i < src_dev->pdata->nr_outconns; i++) { conn = src_dev->pdata->out_conns[i];

•    if (coresight_source_filter(path, conn))
  

•        continue;
       if (conn->dest_dev == dest_dev)
           return conn;
   }
  

@@ -312,7 +360,8 @@ static void coresight_disable_sink(struct coresight_device *csdev) static int coresight_enable_link(struct coresight_device *csdev, struct coresight_device *parent,

•             struct coresight_device *child)
  

•             struct coresight_device *child,
  

•             struct list_head *path)
  

  { int ret = 0; int link_subtype;

@@ -321,8 +370,8 @@ static int coresight_enable_link(struct coresight_device *csdev, if (!parent || !child) return -EINVAL;

• inconn = coresight_find_out_connection(parent, csdev);
• outconn = coresight_find_out_connection(csdev, child);

• inconn = coresight_find_out_connection(parent, csdev, path);
• outconn = coresight_find_out_connection(csdev, child, path); link_subtype = csdev->subtype.link_subtype; if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG &&

IS_ERR(inconn)) @@ -341,7 +390,8 @@ static int coresight_enable_link(struct coresight_device *csdev, static void coresight_disable_link(struct coresight_device *csdev, struct coresight_device *parent,

•               struct coresight_device *child)
  

•               struct coresight_device *child,
  

•               struct list_head *path)
  

  { int i; int link_subtype;

@@ -350,8 +400,8 @@ static void coresight_disable_link(struct coresight_device *csdev, if (!parent || !child) return;

• inconn = coresight_find_out_connection(parent, csdev);
• outconn = coresight_find_out_connection(csdev, child);

• inconn = coresight_find_out_connection(parent, csdev, path);
• outconn = coresight_find_out_connection(csdev, child, path); link_subtype = csdev->subtype.link_subtype; if (link_ops(csdev)->disable) {

@@ -507,7 +557,7 @@ static void coresight_disable_path_from(struct list_head *path, case CORESIGHT_DEV_TYPE_LINK: parent = list_prev_entry(nd, link)->csdev; child = list_next_entry(nd, link)->csdev;

•        coresight_disable_link(csdev, parent, child);
  

•        coresight_disable_link(csdev, parent, child, path);
           break;
       default:
           break;
  

@@ -588,7 +638,7 @@ int coresight_enable_path(struct list_head *path, enum cs_mode mode, case CORESIGHT_DEV_TYPE_LINK: parent = list_prev_entry(nd, link)->csdev; child = list_next_entry(nd, link)->csdev;

•        ret = coresight_enable_link(csdev, parent, child);
  

•        ret = coresight_enable_link(csdev, parent, child, path);
           if (ret)
               goto err;
           break;
  

@@ -802,7 +852,8 @@ static void coresight_drop_device(struct coresight_device *csdev) */ static int _coresight_build_path(struct coresight_device *csdev, struct coresight_device *sink,

•             struct list_head *path)
  

•             struct list_head *path,
  

•             struct coresight_device *source)
  

  { int i, ret; bool found = false;

@@ -814,7 +865,7 @@ static int _coresight_build_path(struct coresight_device *csdev, if (coresight_is_percpu_source(csdev) && coresight_is_percpu_sink(sink) && sink == per_cpu(csdev_sink, source_ops(csdev)->cpu_id(csdev))) {

•    if (_coresight_build_path(sink, sink, path) == 0) {
  

•    if (_coresight_build_path(sink, sink, path, source) == 0) {
           found = true;
           goto out;
       }
  

@@ -825,8 +876,12 @@ static int _coresight_build_path(struct coresight_device *csdev, struct coresight_device *child_dev; child_dev = csdev->pdata->out_conns[i]->dest_dev;

•    if (csdev->pdata->out_conns[i]->source_label &&
  

•        !strstr(kobject_get_path(&source->dev.kobj, GFP_KERNEL),
  

• csdev->pdata->out_conns[i]->source_label))

•        continue;
       if (child_dev &&
  

•        _coresight_build_path(child_dev, sink, path) == 0) {
  

•        _coresight_build_path(child_dev, sink, path, source) ==
  

0. { found = true; break; }

@@ -871,7 +926,7 @@ struct list_head *coresight_build_path(struct coresight_device *source, INIT_LIST_HEAD(path);

• rc = _coresight_build_path(source, sink, path);

• rc = _coresight_build_path(source, sink, path, source); if (rc) { kfree(path); return ERR_PTR(rc);

diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c index 9d550f5697fa..f553fb20966d 100644 --- a/drivers/hwtracing/coresight/coresight-platform.c +++ b/drivers/hwtracing/coresight/coresight-platform.c @@ -205,6 +205,7 @@ static int of_coresight_parse_endpoint(struct device *dev, struct fwnode_handle *rdev_fwnode; struct coresight_connection conn = {}; struct coresight_connection *new_conn;

• const char *label; do { /* Parse the local port details */

@@ -243,6 +244,10 @@ static int of_coresight_parse_endpoint(struct device *dev, conn.dest_fwnode = fwnode_handle_get(rdev_fwnode); conn.dest_port = rendpoint.port;

•    conn.source_label = NULL;
  

•    if (!of_property_read_string(ep, "label", &label))
  

•        conn.source_label = label;
  

•      new_conn = coresight_add_out_conn(dev, pdata, &conn);
       if (IS_ERR_VALUE(new_conn)) {
           fwnode_handle_put(conn.dest_fwnode);
  

diff --git a/include/linux/coresight.h b/include/linux/coresight.h index e8b6e388218c..a9c06ef9bbb2 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -167,6 +167,7 @@ struct coresight_desc { * struct coresight_connection - representation of a single connection * @src_port: a connection's output port number. * @dest_port: destination's input port number @src_port is connected to.

• • @source_label: source component's label.
    • @dest_fwnode: destination component's fwnode handle.
    • @dest_dev: a @coresight_device representation of the component connected to @src_port. NULL until the device is created

@@ -195,6 +196,7 @@ struct coresight_desc { struct coresight_connection { int src_port; int dest_port;

• const char *source_label; struct fwnode_handle *dest_fwnode; struct coresight_device *dest_dev; struct coresight_sysfs_link *link;

-- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK