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Date:   Fri, 29 Oct 2021 11:48:26 -0600
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     Tao Zhang <quic_taozha@quicinc.com>
Cc:     Suzuki K Poulose <suzuki.poulose@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Mike Leach <mike.leach@linaro.org>,
        Leo Yan <leo.yan@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org,
        Tingwei Zhang <quic_tingweiz@quicinc.com>,
        Mao Jinlong <quic_jinlmao@quicinc.com>,
        Yuanfang Zhang <quic_yuanfang@quicinc.com>,
        Trilok Soni <quic_tsoni@quicinc.com>,
        Tingwei Zhang <tingwei@codeaurora.org>
Subject: Re: [PATCH 02/10] coresight: funnel: add support for multiple output
 ports
Message-ID: <20211029174826.GA4083427@p14s>
References: <1634801936-15080-1-git-send-email-quic_taozha@quicinc.com>
 <1634801936-15080-3-git-send-email-quic_taozha@quicinc.com>
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In-Reply-To: <1634801936-15080-3-git-send-email-quic_taozha@quicinc.com>
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Good morning,

On Thu, Oct 21, 2021 at 03:38:48PM +0800, 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 of the trace path.

There isn't any modification in this patch that relates to funnel input ports.

> 
> The source of the input port on funnels will be marked in the
> device tree.
> e.g.
> tpdm_XXX: tpdm@xxxxxxx {
>     ... ... ... ...
> };
> 
> funnel_XXX: funnel@xxxxxxx {
>     ... ... ... ...
>     out-ports {
>         ... ... ... ...
>         port@x {
>             ... ... ... ...
>             label = <&tpdm_XXX>; <-- To point out tpdm_XXX should
>         };                           be outputed from port@x. And
>     ... ... ... ...                  this is a hardware static
>     };                               connections. Here needs
>     ... ... ... ...                  to refer to hardware design.
> };

There is no indication as to why the output port of a funnel needs to be
labelled.  On that topic, twice in the past we have been clear on the fact
that labels should be introduced once the initial functionality has been merged.
And yet this patch is centered entirely on that concept...

> 
> Then driver will parse the source name marked in the device tree, and
> save it to the coresight path. When the function needs to know the
> source name, it could get the source name from coresight path parameter.
> Finally, the output port knows which source it corresponds to, and it
> also knows which input port it corresponds to.
> 
> Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
> Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
> ---
>  drivers/hwtracing/coresight/coresight-core.c  | 75 +++++++++++++++----
>  .../hwtracing/coresight/coresight-platform.c  |  8 ++
>  include/linux/coresight.h                     |  2 +
>  3 files changed, 71 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index 1e621d61307a..490c9d8d43f9 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -56,6 +56,8 @@ static LIST_HEAD(cs_active_paths);
>  const u32 coresight_barrier_pkt[4] = {0x7fffffff, 0x7fffffff, 0x7fffffff, 0x7fffffff};
>  EXPORT_SYMBOL_GPL(coresight_barrier_pkt);
>  
> +static struct coresight_device *coresight_get_source(struct list_head *path);
> +
>  static const struct cti_assoc_op *cti_assoc_ops;
>  
>  void coresight_set_cti_ops(const struct cti_assoc_op *cti_op)
> @@ -121,14 +123,46 @@ static int coresight_source_is_unique(struct coresight_device *csdev)
>  				 csdev, coresight_id_match);
>  }
>  
> +/**
> + * 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_name == NULL)
> +		return ret;
> +
> +	source = coresight_get_source(path);
> +	if (source == NULL)
> +		return ret;
> +
> +	if (is_of_node(source->dev.fwnode))
> +		return strcmp(conn->source_name,
> +			of_node_full_name(to_of_node(source->dev.fwnode)));
> +
> +	return ret;
> +}
> +
>  static int coresight_find_link_inport(struct coresight_device *csdev,
> -				      struct coresight_device *parent)
> +				      struct coresight_device *parent,
> +				      struct list_head *path)
>  {
>  	int i;
>  	struct coresight_connection *conn;
>  
>  	for (i = 0; i < parent->pdata->nr_outport; i++) {
>  		conn = &parent->pdata->conns[i];
> +		if (coresight_source_filter(path, conn))
> +			continue;
>  		if (conn->child_dev == csdev)
>  			return conn->child_port;
>  	}
> @@ -140,13 +174,16 @@ static int coresight_find_link_inport(struct coresight_device *csdev,
>  }
>  
>  static int coresight_find_link_outport(struct coresight_device *csdev,
> -				       struct coresight_device *child)
> +				       struct coresight_device *child,
> +				       struct list_head *path)
>  {
>  	int i;
>  	struct coresight_connection *conn;
>  
>  	for (i = 0; i < csdev->pdata->nr_outport; i++) {
>  		conn = &csdev->pdata->conns[i];
> +		if (coresight_source_filter(path, conn))
> +			continue;
>  		if (conn->child_dev == child)
>  			return conn->outport;
>  	}
> @@ -358,7 +395,8 @@ 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;
> @@ -367,8 +405,8 @@ static int coresight_enable_link(struct coresight_device *csdev,
>  	if (!parent || !child)
>  		return -EINVAL;
>  
> -	inport = coresight_find_link_inport(csdev, parent);
> -	outport = coresight_find_link_outport(csdev, child);
> +	inport = coresight_find_link_inport(csdev, parent, path);
> +	outport = coresight_find_link_outport(csdev, child, path);
>  	link_subtype = csdev->subtype.link_subtype;
>  
>  	if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG && inport < 0)
> @@ -393,7 +431,8 @@ 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, nr_conns;
>  	int link_subtype;
> @@ -402,8 +441,8 @@ static void coresight_disable_link(struct coresight_device *csdev,
>  	if (!parent || !child)
>  		return;
>  
> -	inport = coresight_find_link_inport(csdev, parent);
> -	outport = coresight_find_link_outport(csdev, child);
> +	inport = coresight_find_link_inport(csdev, parent, path);
> +	outport = coresight_find_link_outport(csdev, child, path);
>  	link_subtype = csdev->subtype.link_subtype;
>  
>  	if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG) {
> @@ -518,7 +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;
> @@ -573,7 +612,7 @@ int coresight_enable_path(struct list_head *path, u32 mode, void *sink_data)
>  		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;
> @@ -801,7 +840,8 @@ 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;
> @@ -813,7 +853,7 @@ 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;
>  		}
> @@ -824,8 +864,15 @@ static int _coresight_build_path(struct coresight_device *csdev,
>  		struct coresight_device *child_dev;
>  
>  		child_dev = csdev->pdata->conns[i].child_dev;
> +
> +		if (csdev->pdata->conns[i].source_name &&
> +			is_of_node(source->dev.fwnode) &&
> +		    strcmp(csdev->pdata->conns[i].source_name,
> +				of_node_full_name(to_of_node(source->dev.fwnode))))
> +			continue;
> +

All this seems to be doing is optimize the search graph by not taking the paths
that are not labelled.  As far as I can tell the sink would be found regardless
of this enhancement.  We can think about optimizations for building paths when
it is demonstrated that bottlenecks originate from that part of the code.

>  		if (child_dev &&
> -		    _coresight_build_path(child_dev, sink, path) == 0) {
> +		    _coresight_build_path(child_dev, sink, path, source) == 0) {
>  			found = true;
>  			break;
>  		}
> @@ -870,7 +917,7 @@ 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 c594f45319fc..60c43ab149a5 100644
> --- a/drivers/hwtracing/coresight/coresight-platform.c
> +++ b/drivers/hwtracing/coresight/coresight-platform.c
> @@ -222,6 +222,7 @@ static int of_coresight_parse_endpoint(struct device *dev,
>  	struct of_endpoint endpoint, rendpoint;
>  	struct device_node *rparent = NULL;
>  	struct device_node *rep = NULL;
> +	struct device_node *sn = NULL;
>  	struct device *rdev = NULL;
>  	struct fwnode_handle *rdev_fwnode;
>  	struct coresight_connection *conn;
> @@ -269,6 +270,13 @@ static int of_coresight_parse_endpoint(struct device *dev,
>  		 */
>  		conn->child_fwnode = fwnode_handle_get(rdev_fwnode);
>  		conn->child_port = rendpoint.port;
> +		conn->source_name = NULL;
> +		sn = of_parse_phandle(ep, "label", 0);
> +		if (sn) {
> +			conn->source_name = sn->full_name;
> +			of_node_put(sn);
> +		}

See my comments above on this.  Moreover neither of the yaml files for both
TPDM and TPDA nor the DTS submitted with this patchset account for a "label",
making me very confused about the relevance of this patch.

More comments to come on Monday.

Thanks,
Mathieu

> +
>  		/* Connection record updated */
>  	} while (0);
>  
> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> index 93a2922b7653..7065b60a767b 100644
> --- a/include/linux/coresight.h
> +++ b/include/linux/coresight.h
> @@ -170,6 +170,7 @@ struct coresight_desc {
>   * struct coresight_connection - representation of a single connection
>   * @outport:	a connection's output port number.
>   * @child_port:	remote component's port number @output is connected to.
> + * @source_name:source component's name.
>   * @chid_fwnode: remote component's fwnode handle.
>   * @child_dev:	a @coresight_device representation of the component
>  		connected to @outport.
> @@ -178,6 +179,7 @@ struct coresight_desc {
>  struct coresight_connection {
>  	int outport;
>  	int child_port;
> +	const char *source_name;
>  	struct fwnode_handle *child_fwnode;
>  	struct coresight_device *child_dev;
>  	struct coresight_sysfs_link *link;
> -- 
> 2.17.1
>