HI Anshuman On Wed, 27 Jan 2021 at 08:55, Anshuman Khandual <[email protected]> wrote: > > 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. >
Really need to tighten up the terminology here - I think what you mean is a PE architecturally defined sink - i.e. one that can be determined by reading the feature registers on the PE, rather than an ETR which cannot. However, the Coresight Base System Architecture specification does recommend a per cpu design using an ETR per CPU - now I assume that this case is not catered for in this patch? > 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_PERCPU_PROC. > CORESIGHT_DEV_SUBTYPE_SOURCE_PERCPU_PROC - this does not exist. > > 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 <[email protected]> > Cc: Mike Leach <[email protected]> > Cc: Suzuki K Poulose <[email protected]> > Signed-off-by: Anshuman Khandual <[email protected]> > --- > Changes in V3: > > - Updated coresight_find_default_sink() > > drivers/hwtracing/coresight/coresight-core.c | 16 ++++++++++++++-- > include/linux/coresight.h | 12 ++++++++++++ > 2 files changed, 26 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-core.c > b/drivers/hwtracing/coresight/coresight-core.c > index 0062c89..4795e28 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); > If you do indeed mean the architecturally defined sinks then this could be 'csdev_pe_arch_sink' - or something similar to indicate the reliance on the PE architecture, unless per-cpu ETR topologies are also handled here. > /** > * struct coresight_node - elements of a path, from source to sink > @@ -784,6 +785,13 @@ 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))) { > + _coresight_build_path(sink, sink, path); > + 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 +1007,12 @@ 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/include/linux/coresight.h b/include/linux/coresight.h > index 976ec26..bc3a5ca 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, If this is needed then could it not be ..._SINK_SYSMEM_PROC - to be consistent with ..._SOURCE_PROC? > }; > > 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) All cpu sources are per cpu - that is ETMv3, ETMv4, PTM, ETE - this might be better as simply coresight_is_cpu_source() as all the aforementioned types will return true. > +{ > + 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, > -- > 2.7.4 > Regards Mike -- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK
