[PATCH v2 2/3] coresight: Add source filtering for multi-port output
Suzuki K Poulose
suzuki.poulose at arm.com
Thu Aug 8 08:13:41 PDT 2024
On 08/08/2024 15:43, Tao Zhang wrote:
>
> On 8/7/2024 10:59 PM, Suzuki K Poulose wrote:
>> On 18/07/2024 03:22, Tao Zhang wrote:
>>>
>>> On 7/11/2024 9:05 PM, Suzuki K Poulose wrote:
>>>> On 11/07/2024 09:17, Tao Zhang wrote:
>>>>> In order to enable the output ports of multi-port output devices,
>>>>
>>>> This has nothing to do with multi-port. You wanted to pain the picture
>>>> of a multi-port device, while the reality is different.
>>>>
>>>>> such as static replicator, to correspond to designated sources,
>>>>> a mechanism for filtering data sources is introduced for the
>>>>> output ports.
>>>>>
>>>>> The specified source will be marked like below in the Devicetree.
>>>>> test-replicator {
>>>>> ... ... ... ...
>>>>> out-ports {
>>>>> ... ... ... ...
>>>>> port at 0 {
>>>>> reg = <0>;
>>>>> xxx: endpoint {
>>>>> remote-endpoint = <&xxx>;
>>>>> filter_src = <&xxx>; <-- To specify the source to
>>>>> }; be filtered out here.
>>>>> };
>>>>>
>>>>> port at 1 {
>>>>> reg = <1>;
>>>>> yyy: endpoint {
>>>>> remote-endpoint = <&yyy>;
>>>>> filter_src = <&yyy>; <-- To specify the source to
>>>>> }; be filtered out here.
>>>>> };
>>>>> };
>>>>> };
>>>>>
>>>>> Then driver will find the expected source marked in the Devicetree,
>>>>> and
>>>>> save it to the coresight path. When the function needs to filter the
>>>>> source, 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.
>>>>
>>>> Minor nit: I think the commit description is full of "How" you are
>>>> doing something, while it must rather be: "What and Why?"
>>>>
>>>> I would prefer something like :
>>>>
>>>> Subject: coresight: Add support for trace filtering by source
>>>>
>>>> Some replicators have hard coded filtering of "trace" data, based on
>>>> the
>>>> source device. This is different from the trace filtering based on
>>>> TraceID, available in the standard programmable replicators. e.g.,
>>>> Qualcomm replicators have filtering based on custom trace protocol
>>>> format and is not programmable.
>>>>
>>>> The source device could be connected to the replicator via intermediate
>>>> components (e.g., a funnel). Thus we need platform information from
>>>> the firmware tables to decide the source device corresponding to a
>>>> given output port from the replicator. Given this affects "trace
>>>> path building" and traversing the path back from the sink to source,
>>>> add the concept of "filtering by source" to the generic coresight
>>>> connection.
>>>>
>>> I will update according to your comments to the next version.
>>>>
>>>>>
>>>>> Signed-off-by: Tao Zhang <quic_taozha at quicinc.com>
>>>>> ---
>>>>> drivers/hwtracing/coresight/coresight-core.c | 125
>>>>> ++++++++++++++++--
>>>>> .../hwtracing/coresight/coresight-platform.c | 18 +++
>>>>> include/linux/coresight.h | 5 +
>>>>> 3 files changed, 135 insertions(+), 13 deletions(-)
>>>>>
>>>>> diff --git a/drivers/hwtracing/coresight/coresight-core.c
>>>>> b/drivers/hwtracing/coresight/coresight-core.c
>>>>> index 9fc6f6b863e0..3f02a31b9328 100644
>>>>> --- a/drivers/hwtracing/coresight/coresight-core.c
>>>>> +++ b/drivers/hwtracing/coresight/coresight-core.c
>>>>> @@ -75,15 +75,60 @@ 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;
>>>>> +}
>>>>> +
>>>>
>>>> Why is this still here ? Didn't agree to remove this and pass the
>>>> source
>>>> directly ?
>>>
>>> I agree pass the source directly, but how can we get the source
>>> device of the path
>>>
>>> without this function? The solution I can think of is to pass source
>>> directly from
>>>
>>> "coresight_enable"like below.
>>>
>>> coresight_enable ---pass source---> coresight_enable_path ->
>>> coresight_enable_link
>>>
>>> -> coresight_find_out_connection -> coresight_blocks_source
>>>
>>> Does this solution meet your expectations? Or do you have a better
>>> suggestion?
>>>
>>>>
>>>>> +/**
>>>>> + * coresight_source_filter - checks whether the connection matches
>>>>> the source
>>>>> + * of path if connection is binded to specific source.
>>>>> + * @trace_source: The source device of the trace path
>>>>> + * @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 coresight_device
>>>>> *trace_source,
>>>>> + struct coresight_connection *conn)
>>>>
>>>> This name is a bit confusing. It doesn't tell you, whether it
>>>> allows the trace or blocks it.
>>>>
>>>>> +{
>>>>> + int ret = 0;
>>>>> +
>>>>> + if (!conn->filter_src_dev)
>>>>> + return ret;
>>>>
>>>> This is not the correct check. It must be :
>>>>
>>>> if (!conn->filter_src_fwnode)
>>>>
>>>> Because, the device could have disappeared (or not appeared yet).
>>>> e.g., (TPDM) driver module unloaded/not - loaded.
>>>>
>>>>> +
>>>>> + if (!trace_source)
>>>>
>>>> Is that possible ?
>>>>
>>>>> + return -1;
>>>>> +
>>>>> + if (conn->filter_src_dev == trace_source)
>>>>> + ret = 0;
>>>>> + else
>>>>> + ret = -1;
>>>>
>>>> Couldn't this simply be :
>>>>
>>>> /*
>>>> * Returns true, if the trace path is not possible through @conn
>>>> * for trace originating from @src
>>>> */
>>>> static bool coresight_blocks_source(src, conn)
>>>> {
>>>> return conn->filter_src_fwnode &&
>>>> (conn->filter_src_dev != src);
>>>> }
>>> I will update to the next version.
>>>>
>>>>> +
>>>>> + 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 coresight_device *trace_source)
>>>>
>>>> Please could you rename :
>>>>
>>>> src_dev => csdev
>>>> dest_dev => out_dev
>>>> trace_source => trace_src ?
>>>>
>>>> Having src_dev and trace_source in the same list is confusing.
>>> I will update to the next version.
>>>>
>>>>> {
>>>>> 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(trace_source, conn))
>>>>
>>>> if (coresight_blocks_source(trace_source, conn))
>>>> continue;
>>>>
>>>>> + continue;
>>>>> if (conn->dest_dev == dest_dev)
>>>>> return conn;
>>>>> }
>>>>> @@ -251,7 +296,8 @@ 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 coresight_device *trace_source)
>>>>> {
>>>>> int link_subtype;
>>>>> struct coresight_connection *inconn, *outconn;
>>>>> @@ -259,8 +305,8 @@ 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,
>>>>> trace_source);
>>>>> + outconn = coresight_find_out_connection(csdev, child,
>>>>> trace_source);
>>>>> link_subtype = csdev->subtype.link_subtype;
>>>>> if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG &&
>>>>> IS_ERR(inconn))
>>>>> @@ -273,15 +319,16 @@ 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 coresight_device *trace_source)
>>>>> {
>>>>> struct coresight_connection *inconn, *outconn;
>>>>> 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,
>>>>> trace_source);
>>>>> + outconn = coresight_find_out_connection(csdev, child,
>>>>> trace_source);
>>>>> link_ops(csdev)->disable(csdev, inconn, outconn);
>>>>> }
>>>>> @@ -341,6 +388,9 @@ static void coresight_disable_path_from(struct
>>>>> list_head *path,
>>>>> {
>>>>> u32 type;
>>>>> struct coresight_device *csdev, *parent, *child;
>>>>> + struct coresight_device *source;
>>>>> +
>>>>> + source = coresight_get_source(path);
>>>>
>>>> Grr! This must come from the "caller of the
>>>> coresight_disable_path_from()", which was my comment. Please go back
>>>> and double check the comment on previous version.
>>>
>>> How about if I pass the source to " coresight_disable_path_from"
>>> directly from
>>>
>>> "coresight_enable" or "coresight_disable" like below?
>>>
>>> coresight_enable ----| |--->
>>> coresight_disable_patch_from
>>>
>>> |---pass source---|
>>>
>>> coresight_disable----| |--->
>>> coresight_disable_path -> coresight_disable_patch_from
>>>
>>> This can ensure that the source passed into
>>> coresight_disable_patch_from is
>>>
>>> the correct source.
>>
>> coresight_disable_path_from() must be given the "source" separately,
>> as the "path" could be "partial". Rest could stay as it is in your
>> patch.
> In what scenario is this "path" "partial"?
>
> There are two place where "coresight_disable_path_from" will be called
> in coresight driver.
>
> 1. coresight_disable_path -> coresight_disable_path_from
>
> In this case, I see all "coresight_disable_path" will be called after
> building path successfully. The "path" should
>
> be "complete", right?
>
> 2. coresight_enable_path return with error and call
> coresight_disable_path_from to disable the "path" from
>
> "nd". But in this case, it is called after building path completely,
> right? So this "path" should be complete as well?
>
> Please let me know if there is any mistake in my understanding. If my
> understanding is correct, then there is no
>
> need to pass "source" to "coresight_disable_path_from". Because the
> "source" can be collected from the "path"\
Apologies. You are right. We are passing the full path in both cases.
Instead "nd" is specified for partial path operations.
>
> directly.
>
>>
>>
>>>
>>>>
>>>>
>>>>> if (!nd)
>>>>> nd = list_first_entry(path, struct coresight_node, link);
>>>>> @@ -375,7 +425,7 @@ 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, source);
>>>>> break;
>>>>> default:
>>>>> break;
>>>>> @@ -418,6 +468,9 @@ int coresight_enable_path(struct list_head
>>>>> *path, enum cs_mode mode,
>>>>> u32 type;
>>>>> struct coresight_node *nd;
>>>>> struct coresight_device *csdev, *parent, *child;
>>>>> + struct coresight_device *source;
>>>>> +
>>>>> + source = coresight_get_source(path);
>>>>> list_for_each_entry_reverse(nd, path, link) {
>>>>> csdev = nd->csdev;
>>>>> @@ -456,7 +509,7 @@ 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,
>>>>> source);
>>>>> if (ret)
>>>>> goto err;
>>>>> break;
>>>>> @@ -619,6 +672,7 @@ static void coresight_drop_device(struct
>>>>> coresight_device *csdev)
>>>>> * @csdev: The device to start from.
>>>>> * @sink: The final sink we want in this path.
>>>>> * @path: The list to add devices to.
>>>>> + * @trace_source: The trace source device of the path.
>>>>> *
>>>>> * The tree of Coresight device is traversed until @sink is found.
>>>>> * From there the sink is added to the list along with all the
>>>>> devices that led
>>>>> @@ -627,7 +681,8 @@ 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 *trace_source)
>>>>> {
>>>>> int i, ret;
>>>>> bool found = false;
>>>>> @@ -639,7 +694,7 @@ 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, trace_source)
>>>>> == 0) {
>>>>> found = true;
>>>>> goto out;
>>>>> }
>>>>> @@ -650,8 +705,13 @@ 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]->filter_src_dev
>>>>> + && (csdev->pdata->out_conns[i]->filter_src_dev !=
>>>>> trace_source))
>>>>> + continue;
>>>>> +
>>>>> if (child_dev &&
>>>>> - _coresight_build_path(child_dev, sink, path) == 0) {
>>>>> + _coresight_build_path(child_dev, sink, path,
>>>>> trace_source) == 0) {
>>>>> found = true;
>>>>> break;
>>>>> }
>>>>> @@ -696,7 +756,7 @@ 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);
>>>>> @@ -957,6 +1017,14 @@ static int coresight_orphan_match(struct
>>>>> device *dev, void *data)
>>>>> /* This component still has an orphan */
>>>>> still_orphan = true;
>>>>> }
>>>>
>>>>
>>>>> + if ((conn->filter_src_fwnode) && dst_csdev
>>>>> + && (conn->filter_src_fwnode == dst_csdev->dev.fwnode)) {
>>>>> + conn->filter_src_dev = dst_csdev;
>>>>> + if (conn->filter_src_dev->type
>>>>> + != CORESIGHT_DEV_TYPE_SOURCE)
>>>>> + dev_warn(&conn->filter_src_dev->dev,
>>>>> + "Filter source is not a source device\n");
>>>>> + }
>>>>
>>>> Have you tested your code with the following order :
>>>>
>>>> 1) Build everything as module
>>>> 2) Load the replicator driver.
>>>> 3) Load the TPDM driver
>>>>
>>>> And are you able to get the trace working ? I suspect it doesn't
>>>> work. The csdev->orphan must be used to track if there is any
>>>> missing link
>>>> with unresolved "filter_src_dev".
>>>
>>> I really didn't consider this test case in my testing. There was a
>>> problem with
>>>
>>> the logic of the code I modified. If it is modified to the following,
>>> can it solve the
>>>
>>> test case you proposed?
>>>
>>> static int coresight_orphan_match(struct device *dev, void *data)
>>> {
>>> ... ... ...
>>> for (i = 0; i < src_csdev->pdata->nr_outconns; i++) {
>>> conn = src_csdev->pdata->out_conns[i];
>>>
>>> /*Add the following code to fix filter source device before
>>> skip the port*/
>>> + if ((conn->filter_src_fwnode) && dst_csdev
>>> + && (conn->filter_src_fwnode == dst_csdev->dev.fwnode)) {
>>> + conn->filter_src_dev = dst_csdev;
>>> + if (conn->filter_src_dev->type
>>> + != CORESIGHT_DEV_TYPE_SOURCE)
>>> + dev_warn(&conn->filter_src_dev->dev,
>>> + "Filter source is not a source device\n");
>>
>> And we should not set the device as the filter_src_dev in this case.
>
> Sure, I will update the code as the following.
>
> + if ((conn->filter_src_fwnode) && dst_csdev
> + && (conn->filter_src_fwnode == dst_csdev->dev.fwnode)) {
> + if (dst_csdev->type == CORESIGHT_DEV_TYPE_SOURCE)
> + conn->filter_src_dev = dst_csdev;
> + else
> + dev_warn(&dst_csdev->dev,
> + "Filter source is not a source device\n");
>>
>>> + }
>>>
>>> /* Skip the port if it's already connected. */
>>> if (conn->dest_dev)
>>> continue;
>>> ... ... ...
>>> ret = coresight_add_in_conn(conn);
>>> if (ret)
>>> return ret;
>>>
>>> /* Add the following code to make sure the device
>>> still orphan if there is a
>>>
>>> * filter source firmware node but the filter source
>>> is null.*/
>>>
>>> + if (conn->filter_src_fwnode && !conn->filter_src_dev)
>>> + still_orphan = true;
>>> } else {
>>> /* This component still has an orphan */
>>> still_orphan = true;
>>> }
>>> }
>>>
>>> src_csdev->orphan = still_orphan;
>>> ... ... ...
>>> }
>>>
>>>>
>>>>
>>>>> }
>>>>> src_csdev->orphan = still_orphan;
>>>>> @@ -974,6 +1042,30 @@ static int
>>>>> coresight_fixup_orphan_conns(struct coresight_device *csdev)
>>>>> csdev, coresight_orphan_match);
>>>>> }
>>>>> +/* reset_filter_src - Reset the filter source if the source is
>>>>> being removed */
>>>>> +static int reset_filter_src(struct coresight_device *trace_source,
>>>>> + struct coresight_connection *conn)
>>>>> +{
>>>>> + int i;
>>>>> + int ret = -1;
>>>>> + struct coresight_device *csdev;
>>>>> + struct coresight_connection *output_conn;
>>>>
>>>> I don't think this is sufficient. I would rather walk through the
>>>> entire coresight bus and fixup the filter_src_dev, rather than
>>>> traversing the
>>>> paths. e.g., one of the devices in the path could have been removed.
>>>> See coresight_clear_default_sink() for e.g. You should have something
>>>> similar :
>>>>
>>>> coresight_clear_filter_source();
>>>
>>> That's right. My current understanding is that there are two cases
>>> that need to be considered.
>>>
>>> #1 Unregister the source device
>>>
>>> In this case, we need to walk through the entire coresight bus and
>>> fixup the filter_src_dev
>>>
>>> #2 Unregister the replicator
>>>
>>> Iterate over all output connections to set filter_src_dev and
>>> filter_src_fwnode to NULL.
>>>
>>> Is this logically correct? I have attached my sample code below,
>>> please help review it.
>>>
>>> +static void coresight_clear_filter_source(struct device *dev, void
>>> *data)
>>> +{
>>> + int i;
>>> + struct coresight_device *source = data;
>>> + struct coresight_device *csdev = to_coresight_device(dev);
>>> +
>>> + for (i = 0; i < csdev->pdata->nr_outconns; ++i) {
>>> + if (csdev->pdata->out_conns[i]->filter_src_dev == source)
>>> + csdev->pdata->out_conns[i]->filter_src_dev = NULL;
>>> + }
>>>
>>> +}
>>
>> That looks good to me.
>>
>>>
>>> /* coresight_remove_conns - Remove other device's references to this
>>> device */
>>> static void coresight_remove_conns(struct coresight_device *csdev)
>>> {
>>> int i, j;
>>> struct coresight_connection *conn;
>>>
>>> + if (csdev->type == CORESIGHT_DEV_TYPE_SOURCE) //walk through the
>>> entire coresight bus and fixup the filter_src_dev
>>> + bus_for_each_dev(&coresight_bustype, NULL, csdev,
>>> + coresight_clear_filter_source);
>>>
>>> /*
>>> * Remove the input connection references from the destination
>>> device
>>> * for each output connection.
>>> */
>>> for (i = 0; i < csdev->pdata->nr_outconns; i++) {
>>> conn = csdev->pdata->out_conns[i];
>>> + if (conn->filter_src_fwnode) { //Iterate over all output
>>> connections to set filter_src_dev and filter_src_fwnode to NULL.
>>> + conn->filter_src_dev = NULL;
>>> + conn->filter_src_fwnode = NULL;
>>
>> We may need to "drop" the refcount for this one ?
>
> I'm not clear why need to "drop" the refcount here. I didn't add
> refcount to this patch series before.
Whenever we save a fwnode in a structure, we do : fwnode_handle_get()
and drop them via while releasing it via fwnode_handle_put().
e.g. : of_coresight_parse_endpoint() / acpi_coresight_parse_link() for
connection and dropped in coresight_release_platform_data().
You should do that whenever you save the filter_src_fwnode in
coresight-platform.c and drop ot when the device "using the fwnode" goes
away (in
this case the replicator).
Suzuki
>
> Could you show me your sample code so I can understand what you mean?
>
>
> Best,
>
> Tao
>
>>
>> Suzuki
>>
>>
>>> + }
>>>
>>> if (!conn->dest_dev)
>>> continue;
>>>
>>> ... ... ...
>>> }
>>>
>>>
>>> Best,
>>>
>>> Tao
>>>
>>>>
>>>>
>>>> Suzuki
>>>>
>>>>
>>>>
>>>>> +
>>>>> + csdev = conn->dest_dev;
>>>>> + for (i = 0; i < csdev->pdata->nr_outconns; i++) {
>>>>> + output_conn = csdev->pdata->out_conns[i];
>>>>> + if (output_conn->filter_src_dev
>>>>> + && (output_conn->filter_src_dev == trace_source)) {
>>>>> + output_conn->filter_src_dev = NULL;
>>>>> + return 0;
>>>>> + }
>>>>> + ret = reset_filter_src(trace_source, output_conn);
>>>>> + if (!ret)
>>>>> + return ret;
>>>>> + }
>>>>> + return ret;
>>>>> +}
>>>>> +
>>>>> /* coresight_remove_conns - Remove other device's references to
>>>>> this device */
>>>>> static void coresight_remove_conns(struct coresight_device *csdev)
>>>>> {
>>>>> @@ -986,6 +1078,13 @@ static void coresight_remove_conns(struct
>>>>> coresight_device *csdev)
>>>>> */
>>>>
>>>>
>>>>> for (i = 0; i < csdev->pdata->nr_outconns; i++) {
>>>>> conn = csdev->pdata->out_conns[i];
>>>>> + if (csdev->type == CORESIGHT_DEV_TYPE_SOURCE)
>>>>> + reset_filter_src(csdev, conn);
>>>>> + if (conn->filter_src_fwnode) {
>>>>> + conn->filter_src_dev = NULL;
>>>>> + conn->filter_src_fwnode = NULL;
>>>>> + }
>>>>> +
>>>>> if (!conn->dest_dev)
>>>>> continue;
>>>>> diff --git a/drivers/hwtracing/coresight/coresight-platform.c
>>>>> b/drivers/hwtracing/coresight/coresight-platform.c
>>>>> index 64e171eaad82..b3c3e2361d07 100644
>>>>> --- a/drivers/hwtracing/coresight/coresight-platform.c
>>>>> +++ b/drivers/hwtracing/coresight/coresight-platform.c
>>>>> @@ -243,6 +243,24 @@ static int of_coresight_parse_endpoint(struct
>>>>> device *dev,
>>>>> conn.dest_fwnode = fwnode_handle_get(rdev_fwnode);
>>>>> conn.dest_port = rendpoint.port;
>>>>> + /*
>>>>> + * Get the firmware node of the filter source through the
>>>>> + * reference. This could be used to filter the source in
>>>>> + * building path.
>>>>> + */
>>>>> + conn.filter_src_fwnode =
>>>>> + fwnode_find_reference(&ep->fwnode, "filter-src", 0);
>>>>> + if (IS_ERR(conn.filter_src_fwnode))
>>>>> + conn.filter_src_fwnode = NULL;
>>>>> + else {
>>>>> + conn.filter_src_dev =
>>>>> + coresight_find_csdev_by_fwnode(conn.filter_src_fwnode);
>>>>> + if (conn.filter_src_dev && (conn.filter_src_dev->type
>>>>> + != CORESIGHT_DEV_TYPE_SOURCE))
>>>>> + dev_warn(&conn.filter_src_dev->dev,
>>>>> + "Filter source %s is not a source device\n");
>>>>> + }
>>>>> +
>>>>> 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 f09ace92176e..91a689b4514b 100644
>>>>> --- a/include/linux/coresight.h
>>>>> +++ b/include/linux/coresight.h
>>>>> @@ -172,6 +172,9 @@ struct coresight_desc {
>>>>> * @dest_dev: a @coresight_device representation of the component
>>>>> connected to @src_port. NULL until the device is created
>>>>> * @link: Representation of the connection as a sysfs link.
>>>>> + * @filter_src_fwnode: filter source component's fwnode handle.
>>>>> + * @filter_src_dev: a @coresight_device representation of the
>>>>> component that
>>>>> + needs to be filtered.
>>>>> *
>>>>> * The full connection structure looks like this, where in_conns
>>>>> store
>>>>> * references to same connection as the source device's out_conns.
>>>>> @@ -200,6 +203,8 @@ struct coresight_connection {
>>>>> struct coresight_device *dest_dev;
>>>>> struct coresight_sysfs_link *link;
>>>>> struct coresight_device *src_dev;
>>>>> + struct fwnode_handle *filter_src_fwnode;
>>>>> + struct coresight_device *filter_src_dev;
>>>>> atomic_t src_refcnt;
>>>>> atomic_t dest_refcnt;
>>>>> };
>>>>
>>
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