From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 746B41878; Thu, 18 Jul 2024 02:22:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.168.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721269359; cv=none; b=KefAYhveI7L/xzVPyBAPieOIlq64bl6lF35OBJ0c5uSm/Ivt2rqLhplB1kY+9p5Kvas0ld84rbVf6VmyvtqK0KiaTSOLaYPAJxnN2PCqXDRKG5UPXNN2HPlkAWqFahIltwDO2BWsBOtN/oFo16n5QnwsWnYo2gdlQAhrouz/nkM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721269359; c=relaxed/simple; bh=Z2EgqyX0dteja6pmyZBQ6+wgyaf/zSmY7AEEIdkzu2c=; h=Message-ID:Date:MIME-Version:From:Subject:To:CC:References: In-Reply-To:Content-Type; b=tVDGfp3e1ZmRtXJ3Nkdi2hpOev745ND7pcCSUE5/oiml6msAOrxomAjwC+D9ScMnIj3XDpfxnv28TrihCVmruAt3ZZwUn4C6fH8tNm24yk6YAaPdHneJeuntMhKBAcVPAY0RB7DccsdAi0xa1PFEaffzN60P9Tq0I5qZ0nNpNuk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=quicinc.com; spf=pass smtp.mailfrom=quicinc.com; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b=NUA/M3Zy; arc=none smtp.client-ip=205.220.168.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=quicinc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=quicinc.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b="NUA/M3Zy" Received: from pps.filterd (m0279864.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 46I12rWJ012853; Thu, 18 Jul 2024 02:22:13 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=qcppdkim1; bh= XMWebLtRQlSOyOEeqh5om3Vyexczwth7Fx43sXKT7fQ=; b=NUA/M3ZyAwuF7IWo aT2+kZrGmRjD2pikFoDplYW65mqJW5Vs3YWIbEvZMKeGhXdk7dv5hx7mnZ+g79Vk 0i+i+22hUtShWDP0t3gzQjjMH0rfHxu91ZeqiTh4hIoE7jhlMHrQ+R6d9TJeQtZu 4qujXoINypiSPsA0BjQbZ5cTI6aeEPyOm4mmTuzzusYZtlaC9ZvEUYr8om+KexiD tJCX+tsP7YK/p+R+04Y7e7H1AW2s9Sy9sACgP9Jof5uTxCffIghLjzXJtkW/usHv ucR/TRr5SlUxcd24/ZzEomNMhtAQzuYWG8Ghzu5fP9PETsN1FErqcC3ZlEedoThk rVSU6g== Received: from nalasppmta02.qualcomm.com (Global_NAT1.qualcomm.com [129.46.96.20]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 40es1wr3k1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 18 Jul 2024 02:22:12 +0000 (GMT) Received: from nalasex01c.na.qualcomm.com (nalasex01c.na.qualcomm.com [10.47.97.35]) by NALASPPMTA02.qualcomm.com (8.17.1.19/8.17.1.19) with ESMTPS id 46I2MCJC031595 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 18 Jul 2024 02:22:12 GMT Received: from [10.239.133.211] (10.80.80.8) by nalasex01c.na.qualcomm.com (10.47.97.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Wed, 17 Jul 2024 19:22:08 -0700 Message-ID: Date: Thu, 18 Jul 2024 10:22:06 +0800 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Tao Zhang Subject: Re: [PATCH v2 2/3] coresight: Add source filtering for multi-port output To: Suzuki K Poulose , Mike Leach , James Clark , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Mathieu Poirier , Leo Yan , Alexander Shishkin CC: , , , , References: <20240711081750.21792-1-quic_taozha@quicinc.com> <20240711081750.21792-3-quic_taozha@quicinc.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01c.na.qualcomm.com (10.47.97.35) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: QtmQ7oEoqOwB58onSHeXH3Pto4S2sFln X-Proofpoint-ORIG-GUID: QtmQ7oEoqOwB58onSHeXH3Pto4S2sFln X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.28.16 definitions=2024-07-17_19,2024-07-17_02,2024-05-17_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 spamscore=0 mlxscore=0 bulkscore=0 adultscore=0 impostorscore=0 priorityscore=1501 phishscore=0 clxscore=1015 suspectscore=0 malwarescore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2407110000 definitions=main-2407180014 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@0 { >>              reg = <0>; >>              xxx: endpoint { >>                  remote-endpoint = <&xxx>; >>                  filter_src = <&xxx>; <-- To specify the source to >>              };                           be filtered out here. >>          }; >> >>          port@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 >> --- >>   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. > > >>         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"); +        }         /* 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; +    } +} /* 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; +        }         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; >>   }; >