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

Hi,

On Mon, 15 Apr 2024 at 14:24, Suzuki K Poulose suzuki.poulose@arm.com wrote:

On 09/04/2024 14:22, Tao Zhang wrote:

...

On 4/9/2024 3:13 PM, Suzuki K Poulose wrote:

...

Hi

On 29/03/2024 09:27, Tao Zhang 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.

I think there is still a bit of confusion. By "Dynamic" I mean, the "dynamic funnel" (explicit port enablement via MMIO) vs "static funnel" (no programming, always ON).

So, coming to your example, do we need to "explicitly" enable trace flow for an "input" and/or an "output" port in your "funnel" ?

Sorry for my misunderstanding in the previous mails. Our funnels are programmable just like the common dynamic funnels.

In our solution, we just make funnels have multiple output ports connected to different devices or ports. When we use it, we still

enable the input port through programming. Our solution is to know which input port the expected data comes from based on the

source label corresponding to the output port. This way we can build the expected trace path. In other respects, it is used the same

as common dynamic funnels.

Ok. So, to summarise :

1. This is not a standard Funnel, but a trace link with multiple-input and multiple-output, with inputs hardwired to an outline at integration.
2. The programming model is same as that of a "standard funnel".

Now, we do have enough information in the coresight_connections to traverse input/output ports. But we need additional logic to "hardwire" the ports to each other and necessary logic to handle the

There are two options here :

1. Treat this as a new component and have its own driver, with additional logic to handle the input/output wiring.

2. Drive it using the funnel driver, with a a new compatible and add additional logic to handle the input/output wiring.

My inclination is towards (2), we need to see how this works out.

We need to irrespective of the options, we need special handling for hardwired ports in 1) building path 2) walking back the path (in TPDA driver)

We also need some "DT" information to bind a given input port to an output port. We must not use "any device" labels to hack this up, like the approach in this series.

Given that the internal connections are static for the given device, then the compatible will imply these connections in just the same way as the arm,coresight-funnel implies that all inputs are connected to the single output.

Irrespective of if a new driver is used, or an extension to the current funnel driver to handle a new compatible - the mapping between input and output ports are created based on the compatible..

As we are building a path from source to sink, what is then needed is a method in the generic path building code, to recognise these amppings and filter the output ports that are searched based on the input port in use.

On standard components, where the mapping is not present, then the code will continue as it does now, for these compound funnels, the mappings will be present and the output filtering will occur. This removes the need for the labels / extra connection attributes on devices other than the funnel, and also removes the need to specify the internal connections as part of the device tree.

Regards

Mike

Rob/Krzysztof,

Do you have any recommendations for describing the 'hard wired ports' ?

e.g:

component { input_ports { component_input_port0: port@0 { ... <hard-wired-to*> = &component_output_port0; }; ... };

output_ports { componentne_output_port0: port@0 { ... <hard-wired-to> = &component_input_port0; }; ... };

};

*Need a better suitable property than "hard-wired-to".

Suzuki

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Best,

Tao

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...

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

i.e, Like TMC-ETF in HWFIFO mode. In this mode, the TMC-ETF is acting like a cache for easing ATB data load, by providing h/w buffering. (In your case, it may not be providing any buffering, it doesn't matter either way, as it is not visible to the driver).

Suzuki

...

of this. Could you describe it in detail?

Best,

Tao

...

Suzuki

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Signed-off-by: Tao Zhang quic_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;