RE: [PATCH 0/9 v2] Coresight framework and drivers

[Al Grant]

> This set is addressing comments received after the May 30th
> submission[1].  More specifically:
>
> .All drivers have been converted to use the AMBA bus
>  interface.
> .Debugfs entries are now created with a macro.
> .A header file was created for the ETM driver to allow
>  for the reuse of constant definition.
> .Error path on some drivers have been corrected.
> .All types converted from uintX_t to uX.
> .All numeric constant have been replaced with #defines and
>  comments added where necessary.
> .Removal of "coresight-id" and "coresigh-name" DT bindings.
> .Move all DT connections specification to use the generic
>  graph bindings.
> .The removal of the replicator driver since it doesn't show
>  on the AMBA bus.  Drivers for enhanced replicators that have
>  a configuration space can be added when the need arises.

So now any source or link can have multiple output ports.  But you
still have a device type CORESIGHT_DEV_SUBTYPE_LINK_SPLIT, which is
now unused.  Is CORESIGHT_DEV_SUBTYPE_LINK_SPLIT there just for
future programmable replicators?

It would be simpler if you kept the separate replicator component,
even for non-programmable replicators.  Then a node can be a merge
node (multiple inputs) or split node (multiple outputs) but not both.

Also, the global curr_sink limits you to one trace sink device.
It will need changing for systems with multiple ETBs, or where
people want to route one trace source to an ETB and another to a TPIU.

One way to support this (without exposing the full topology to the
user) would be to have a trace sink per trace source.  So instead of
switching the sink system-wide, the user would switch the sink for
each source.  You would then run into the problem that some valid
end states cannot be reached by individually changing the sink of
each source, but the sources would have to be changed as a group.

For example:

  cpu #0 --funnel--replicator--tpiu
  cpu #1 -/                  \-etb

  stm ---------etf-------------etr

CPU #0 and CPU #1 have to go to the same place (unless you have a
programmable filtering replicator) but STM goes to a different place.
You need an interface that lets you set the destination for multiple
devices, either to a specific trace sink, or expressed in terms of
intent (on-chip vs. off-chip) with the ability to read back to find
out where you'll actually find the trace for any given source.

Al


>
> Regards,
> Mathieu
>
> [1]. http://thread.gmane.org/gmane.linux.kernel/1714785
>
> Mathieu Poirier (3):
>   coresight: adding support for beagle and beagleXM
>   coresight: adding basic support for Vexpress TC2
>   ARM: removing support for etb/etm in "arch/arm/kernel/"
>
> Pratik Patel (6):
>   coresight: add CoreSight core layer framework
>   coresight-tmc: add CoreSight TMC driver
>   coresight-tpiu: add CoreSight TPIU driver
>   coresight-etb: add CoreSight ETB driver
>   coresight-funnel: add CoreSight Funnel driver
>   coresight-etm: add CoreSight ETM/PTM driver
>
>  .../devicetree/bindings/arm/coresight.txt          |  141 ++
>  arch/arm/boot/dts/omap3-beagle-xm.dts              |   28 +
>  arch/arm/boot/dts/omap3-beagle.dts                 |   28 +
>  arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts         |  174 +++
>  arch/arm/include/asm/hardware/coresight.h          |  157 --
>  arch/arm/include/asm/hardware/cp14.h               |  540 +++++++
>  arch/arm/kernel/Makefile                           |    1 -
>  arch/arm/kernel/etm.c                              |  654 ---------
>  arch/arm/kernel/hw_breakpoint.c                    |    4 +-
>  arch/arm/mach-omap2/Kconfig                        |    8 -
>  arch/arm/mach-omap2/Makefile                       |    1 -
>  arch/arm/mach-omap2/emu.c                          |   50 -
>  drivers/Kconfig                                    |    2 +
>  drivers/Makefile                                   |    1 +
>  drivers/amba/bus.c                                 |    2 +-
>  drivers/coresight/Kconfig                          |   39 +
>  drivers/coresight/Makefile                         |    8 +
>  drivers/coresight/coresight-etb.c                  |  557 ++++++++
>  drivers/coresight/coresight-etm-cp14.c             |  506 +++++++
>  drivers/coresight/coresight-etm.c                  | 1507
> ++++++++++++++++++++
>  drivers/coresight/coresight-etm.h                  |  192 +++
>  drivers/coresight/coresight-funnel.c               |  252 ++++
>  drivers/coresight/coresight-priv.h                 |   69 +
>  drivers/coresight/coresight-tmc.c                  |  791
> ++++++++++
>  drivers/coresight/coresight-tpiu.c                 |  223 +++
>  drivers/coresight/coresight.c                      |  680 +++++++++
>  drivers/coresight/of_coresight.c                   |  207 +++
>  include/linux/amba/bus.h                           |    1 +
>  include/linux/coresight.h                          |  190 +++
>  include/linux/of_coresight.h                       |   27 +
>  30 files changed, 6166 insertions(+), 874 deletions(-)
>  create mode 100644
> Documentation/devicetree/bindings/arm/coresight.txt
>  delete mode 100644 arch/arm/include/asm/hardware/coresight.h
>  create mode 100644 arch/arm/include/asm/hardware/cp14.h
>  delete mode 100644 arch/arm/kernel/etm.c
>  delete mode 100644 arch/arm/mach-omap2/emu.c
>  create mode 100644 drivers/coresight/Kconfig
>  create mode 100644 drivers/coresight/Makefile
>  create mode 100644 drivers/coresight/coresight-etb.c
>  create mode 100644 drivers/coresight/coresight-etm-cp14.c
>  create mode 100644 drivers/coresight/coresight-etm.c
>  create mode 100644 drivers/coresight/coresight-etm.h
>  create mode 100644 drivers/coresight/coresight-funnel.c
>  create mode 100644 drivers/coresight/coresight-priv.h
>  create mode 100644 drivers/coresight/coresight-tmc.c
>  create mode 100644 drivers/coresight/coresight-tpiu.c
>  create mode 100644 drivers/coresight/coresight.c
>  create mode 100644 drivers/coresight/of_coresight.c
>  create mode 100644 include/linux/coresight.h
>  create mode 100644 include/linux/of_coresight.h
>
> --
> 1.9.1
>


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