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

18 Apr 2024

      Hi Mike
On 18/04/2024 09:48, Mike Leach wrote:
...
Hi Suzuki
On Wed, 17 Apr 2024 at 10:21, Suzuki K Poulose suzuki.poulose@arm.com wrote:
...
Hi Mike
On 16/04/2024 15:19, Mike Leach wrote:
...
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 :

This is not a standard Funnel, but a trace link with multiple-input
   and multiple-output, with inputs hardwired to an outline at
   integration.
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 :

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

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.
I am sorry, I couldn't follow the last part. We have two or more output
ports and we need a way to identify, which input port is hardwired to
output-port0 and output-port1. Given we need special handling for these
anyway, I would like to avoid hard coding the input-output connection.
i.e., we do not want to assume that input-0  is always => output-0.
If we regard the current component as having compatible
"qcom,coresight-compound-funnel-v1", then this identifies the
relationship between the in-ports and out-ports.
So the new driver / extension to the funnel driver that handles this
compatible with know the static mapping between input and output so
program it.
Ok, but like I said, having one compatible may not be enough to know
the "static" mapping for all possible device instances on different
SoCs.
...
If however you want a more generic approach to handle future different
versions of the component, then of course a method in DT of mapping
in-ports to out-ports is useful.
If did wonder if something along the lines of:-
compound-funnel@0x1234000 {
      compatible = "compound-funnel"
      regs = < 0x1234000 0x1000>
       sub-funnel@0 {
                  in-ports {
                         [some port definitions]
                   }
                  out-ports {
                        [some port definitions]
                   }
        }
       sub-funnel@1 {
                  in-ports {
                         [some port definitions]
                   }
                  out-ports {
                        [some port definitions]
                  }
         }
}
That would work, with "two" different coresight devices for each
"embedded funnel". And that also confuses the user with the topology.
...
might be made to work? not sure about the implications of having more
that one set of in-ports and out-ports in a component in the device
tree & would need specific handling in the driver to iterate
sub-funnels.
...
...
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.
Agreed. We could mark this as a property of the
port/coresight_connection.
...
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.
Agreed
...
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.
I am still not clear how we map the input-output ports. Rest is what
exactly I had in mind. So, once we sort out the port mapping
we could proceed to the prototyping.
given we iterate by output port index into an array of out ports, and
have an array of in-ports by index, a third mapping array, same size
as in-ports, determining the associated out port index should suffice.
Mapping array should be optional - if not there, path discovery works
as previously
We could simply add a "(sticky)flag" to the 
"coresight_connection".src_port/dest_port and extend the array to
include the sticky_port for src/dest port and use that flag to force
the path traversal.
Suzuki
...
Regards
Mike
...
Kind regards
Suzuki
...
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
...
Best,
Tao
...
>
> "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
>>
>>>
>>> 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;
>>

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