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Message-ID: <20210317193136.GB1498234@xps15>
Date: Wed, 17 Mar 2021 13:31:36 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Suzuki K Poulose <suzuki.poulose@....com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
mike.leach@...aro.org, anshuman.khandual@....com,
leo.yan@...aro.org
Subject: Re: [PATCH v4 17/19] coresight: core: Add support for dedicated
percpu sinks
On Thu, Feb 25, 2021 at 07:35:41PM +0000, Suzuki K Poulose wrote:
> From: Anshuman Khandual <anshuman.khandual@....com>
>
> Add support for dedicated sinks that are bound to individual CPUs. (e.g,
> TRBE). To allow quicker access to the sink for a given CPU bound source,
> keep a percpu array of the sink devices. Also, add support for building
> a path to the CPU local sink from the ETM.
>
> This adds a new percpu sink type CORESIGHT_DEV_SUBTYPE_SINK_PERCPU_SYSMEM.
> This new sink type is exclusively available and can only work with percpu
> source type device CORESIGHT_DEV_SUBTYPE_SOURCE_PROC.
>
> This defines a percpu structure that accommodates a single coresight_device
> which can be used to store an initialized instance from a sink driver. As
> these sinks are exclusively linked and dependent on corresponding percpu
> sources devices, they should also be the default sink device during a perf
> session.
>
> Outwards device connections are scanned while establishing paths between a
> source and a sink device. But such connections are not present for certain
> percpu source and sink devices which are exclusively linked and dependent.
> Build the path directly and skip connection scanning for such devices.
>
> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> Cc: Mike Leach <mike.leach@...aro.org>
> Cc: Suzuki K Poulose <suzuki.poulose@....com>
> Tested-by: Suzuki K Poulose <suzuki.poulose@....com>
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> [Moved the set/get percpu sink APIs from TRBE patch to here]
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> ---
> Changes:
> - Export methods to set/get percpu sinks for fixing module
> build for TRBE
> - Addressed coding style comments (Suzuki)
> - Check status of _coresight_build_path() (Mathieu)
> ---
> drivers/hwtracing/coresight/coresight-core.c | 29 ++++++++++++++++++--
> drivers/hwtracing/coresight/coresight-priv.h | 3 ++
> include/linux/coresight.h | 12 ++++++++
> 3 files changed, 42 insertions(+), 2 deletions(-)
Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
>
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index 0062c8935653..55c645616bf6 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -23,6 +23,7 @@
> #include "coresight-priv.h"
>
> static DEFINE_MUTEX(coresight_mutex);
> +DEFINE_PER_CPU(struct coresight_device *, csdev_sink);
>
> /**
> * struct coresight_node - elements of a path, from source to sink
> @@ -70,6 +71,18 @@ void coresight_remove_cti_ops(void)
> }
> EXPORT_SYMBOL_GPL(coresight_remove_cti_ops);
>
> +void coresight_set_percpu_sink(int cpu, struct coresight_device *csdev)
> +{
> + per_cpu(csdev_sink, cpu) = csdev;
> +}
> +EXPORT_SYMBOL_GPL(coresight_set_percpu_sink);
> +
> +struct coresight_device *coresight_get_percpu_sink(int cpu)
> +{
> + return per_cpu(csdev_sink, cpu);
> +}
> +EXPORT_SYMBOL_GPL(coresight_get_percpu_sink);
> +
> static int coresight_id_match(struct device *dev, void *data)
> {
> int trace_id, i_trace_id;
> @@ -784,6 +797,14 @@ static int _coresight_build_path(struct coresight_device *csdev,
> if (csdev == sink)
> goto out;
>
> + 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) {
> + found = true;
> + goto out;
> + }
> + }
> +
> /* Not a sink - recursively explore each port found on this element */
> for (i = 0; i < csdev->pdata->nr_outport; i++) {
> struct coresight_device *child_dev;
> @@ -999,8 +1020,12 @@ coresight_find_default_sink(struct coresight_device *csdev)
> int depth = 0;
>
> /* look for a default sink if we have not found for this device */
> - if (!csdev->def_sink)
> - csdev->def_sink = coresight_find_sink(csdev, &depth);
> + if (!csdev->def_sink) {
> + if (coresight_is_percpu_source(csdev))
> + csdev->def_sink = per_cpu(csdev_sink, source_ops(csdev)->cpu_id(csdev));
> + if (!csdev->def_sink)
> + csdev->def_sink = coresight_find_sink(csdev, &depth);
> + }
> return csdev->def_sink;
> }
>
> diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
> index f5f654ea2994..ff1dd2092ac5 100644
> --- a/drivers/hwtracing/coresight/coresight-priv.h
> +++ b/drivers/hwtracing/coresight/coresight-priv.h
> @@ -232,4 +232,7 @@ coresight_find_csdev_by_fwnode(struct fwnode_handle *r_fwnode);
> void coresight_set_assoc_ectdev_mutex(struct coresight_device *csdev,
> struct coresight_device *ect_csdev);
>
> +void coresight_set_percpu_sink(int cpu, struct coresight_device *csdev);
> +struct coresight_device *coresight_get_percpu_sink(int cpu);
> +
> #endif
> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> index 976ec2697610..8a3a3c199087 100644
> --- a/include/linux/coresight.h
> +++ b/include/linux/coresight.h
> @@ -50,6 +50,7 @@ enum coresight_dev_subtype_sink {
> CORESIGHT_DEV_SUBTYPE_SINK_PORT,
> CORESIGHT_DEV_SUBTYPE_SINK_BUFFER,
> CORESIGHT_DEV_SUBTYPE_SINK_SYSMEM,
> + CORESIGHT_DEV_SUBTYPE_SINK_PERCPU_SYSMEM,
> };
>
> enum coresight_dev_subtype_link {
> @@ -428,6 +429,17 @@ static inline void csdev_access_write64(struct csdev_access *csa, u64 val, u32 o
> csa->write(val, offset, false, true);
> }
>
> +static inline bool coresight_is_percpu_source(struct coresight_device *csdev)
> +{
> + return csdev && (csdev->type == CORESIGHT_DEV_TYPE_SOURCE) &&
> + (csdev->subtype.source_subtype == CORESIGHT_DEV_SUBTYPE_SOURCE_PROC);
> +}
> +
> +static inline bool coresight_is_percpu_sink(struct coresight_device *csdev)
> +{
> + return csdev && (csdev->type == CORESIGHT_DEV_TYPE_SINK) &&
> + (csdev->subtype.sink_subtype == CORESIGHT_DEV_SUBTYPE_SINK_PERCPU_SYSMEM);
> +}
> #else /* !CONFIG_64BIT */
>
> static inline u64 csdev_access_relaxed_read64(struct csdev_access *csa,
> --
> 2.24.1
>
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