Re: [PATCH v5 08/14] coresight: cti: Enable CTI associated with devices.

Suzuki Kuruppassery Poulose
2019-11-29T18:28:28Z

On 19/11/2019 23:19, Mike Leach wrote:
> The CoreSight subsystem enables a path of devices from source to sink.
> Any CTI devices associated with the path devices must be enabled at the
> same time.
>
> This patch adds an associated coresight_device element to the main
> coresight device structure, and uses this to create associations between
> the CTI and other devices based on the device tree data. The associated
> device element is used to enable CTI in conjunction with the path elements.
>
> CTI devices are reference counted so where a single CTI is associated with
> multiple elements on the path, it will be enabled on the first associated
> device enable, and disabled with the last associated device disable.
>
> Signed-off-by: Mike Leach <mike.leach@linaro.org>
> ---
> drivers/hwtracing/coresight/coresight-cti.c | 87 +++++++++++++++++++
> .../hwtracing/coresight/coresight-platform.c | 23 +++++
> drivers/hwtracing/coresight/coresight-priv.h | 6 ++
> drivers/hwtracing/coresight/coresight.c | 58 +++++++++++--
> include/linux/coresight.h | 5 ++
> 5 files changed, 173 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-cti.c b/drivers/hwtracing/coresight/coresight-cti.c
> index 369488dd7b8e..cf116463149a 100644
> --- a/drivers/hwtracing/coresight/coresight-cti.c
> +++ b/drivers/hwtracing/coresight/coresight-cti.c
> @@ -440,6 +440,90 @@ int cti_channel_setop(struct device *dev, enum cti_chan_set_op op,
> return err;
> }
>
> +/*
> + * Look for a matching connection device name in the list of
> + * connections. If found then swap in the csdev name and return
> + * found.
> + */
> +static bool
> +cti_match_con_name(struct cti_device *ctidev, const char *node_name,
> + const char *csdev_name)

Here we actually fixup the name of the connection, rather than simply
matching it. So it may be apt to rename this to cti_match_fixup_name()

> +{
> + struct cti_trig_con *trig_con;
> +
> + list_for_each_entry(trig_con, &ctidev->trig_cons, node) {
> + if (trig_con->con_dev_name) {
> + if (!strcmp(node_name, trig_con->con_dev_name)) {

Can there be duplicate node_name's ? Does it make sense to store the
fwhandle along with the "temporary node_name" to match it later while
fixing up ?

> + /* match: so swap in csdev name */
> + kfree(trig_con->con_dev_name);
> + trig_con->con_dev_name =
> + kstrdup(csdev_name, GFP_KERNEL);
> + return true;
> + }
> + }
> + }
> + return false;
> +}

> +/*
> + * Search the cti list to add an associated CTI into the supplied CS device
> + * This will set the association if CTI declared before the CS device
> + */
> +void cti_add_assoc_to_csdev(struct coresight_device *csdev)
> +{

..

> + struct cti_drvdata *ect_item;
> + struct cti_device *ctidev;
> + const char *node_name = NULL, *csdev_name;
> +
> + /* protect the list */
> + mutex_lock(&ect_mutex);
> +
> + /* exit if current is an ECT device.*/
> + if ((csdev->type == CORESIGHT_DEV_TYPE_ECT) || list_empty(&ect_net))
> + goto cti_add_done;
> +
> + /* if we didn't find the csdev previously we used the fwnode name */
> + node_name = coresight_get_fwnode_name(csdev->dev.parent);

We used "cti_plat_get_node_name()" when we added the name in the
absence of csdev in patch 7, could we not reuse the function here ?

> +
> + if (!node_name)
> + goto cti_add_done;
> +
> + /* this is the name we want to use for the association */
> + csdev_name = dev_name(&csdev->dev);

> +
> + /* for each CTI in list... */
> + list_for_each_entry(ect_item, &ect_net, node) {
> + ctidev = &ect_item->ctidev;
> + if (cti_match_con_name(ctidev, node_name, csdev_name)) {
> + /*
> + * if we found a matching name then update the
> + * association pointers.
> + */
> + csdev->ect_dev = ect_item->csdev;
> + goto cti_add_done;

break; instead ?

> + }
> + }
> +cti_add_done:
> + mutex_unlock(&ect_mutex);
> +}
> +EXPORT_SYMBOL_GPL(cti_add_assoc_to_csdev);
> +
> +/*
> + * Update the cross references where the associated device was found
> + * while we were building the connection info. This will occur if the
> + * assoc device was registered before the CTI.
> + */
> +static void cti_update_conn_xrefs(struct cti_drvdata *drvdata)
> +{
> + struct cti_trig_con *tc;
> + struct cti_device *ctidev = &drvdata->ctidev;
> +
> + list_for_each_entry(tc, &ctidev->trig_cons, node) {
> + if (tc->con_dev)
> + tc->con_dev->ect_dev = drvdata->csdev;
> + }

Does this need to take the coresight_mutex to avoid racing against
a coresight_enable_path() ? Though this may be fine as long as the
CTI driver detects that that device was not enabled.

Also, it looks like we have a potential issue with perf vs sysfs mode.
The perf mode doesn't seem to take the coresight_mutex, for
build_path/enable_path operations. This is outside the scope of this
series though.

> +}
> +
> /** cti ect operations **/
> int cti_enable(struct coresight_device *csdev)
> {
> @@ -574,6 +658,9 @@ static int cti_probe(struct amba_device *adev, const struct amba_id *id)
> drvdata->csdev_release = drvdata->csdev->dev.release;
> drvdata->csdev->dev.release = cti_device_release;
>
> + /* set any cross references */
> + cti_update_conn_xrefs(drvdata);
> +
/* all done - dec pm refcount */
> pm_runtime_put(&adev->dev);
> dev_info(&drvdata->csdev->dev, "CTI initialized\n");
> diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c
> index 3c5bee429105..6721cb1af5fe 100644
> --- a/drivers/hwtracing/coresight/coresight-platform.c
> +++ b/drivers/hwtracing/coresight/coresight-platform.c
> @@ -293,6 +293,12 @@ static int of_get_coresight_platform_data(struct device *dev,
>
> return 0;
> }
> +
> +static inline const char *of_coresight_get_node_name(struct device *dev)
> +{
> + return dev->of_node->full_name;
> +}
> +
> #else
> static inline int
> of_get_coresight_platform_data(struct device *dev,
> @@ -305,6 +311,11 @@ static inline int of_coresight_get_cpu(struct device *dev)
> {
> return -ENODEV;
> }
> +
> +static inline const char *of_coresight_get_node_name(struct device *dev)
> +{
> + return NULL;
> +}
> #endif
>
> #ifdef CONFIG_ACPI
> @@ -766,6 +777,18 @@ static inline int acpi_coresight_get_cpu(struct device *dev)
> }
> #endif
>
> +const char *coresight_get_fwnode_name(struct device *dev)

As mentioned above, please could we reuse the name helper we used
during the insertion rather than introducing a new wrapper which
effectively does the same thing ?

> +{
> + const char *node_name = NULL;
> + struct fwnode_handle *fwnode = dev_fwnode(dev);
> +
> + if (is_of_node(fwnode))
> + node_name = of_coresight_get_node_name(dev);
> +
> + return node_name;
> +}
> +EXPORT_SYMBOL_GPL(coresight_get_fwnode_name);

Why does this get exported ? If a following patch needs it, you may
always do that when you need it.

Cheers
Suzuki