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* [PATCH v4 0/6] coresight: etm4x: save/restore ETMv4 context across CPU low power states
@ 2019-07-30 12:51 Andrew Murray
  2019-07-30 12:51 ` [PATCH v4 1/6] coresight: etm4x: remove superfluous setting of os_unlock Andrew Murray
                   ` (6 more replies)
  0 siblings, 7 replies; 27+ messages in thread
From: Andrew Murray @ 2019-07-30 12:51 UTC (permalink / raw)
  To: Mathieu Poirier, Suzuki K Poulose, Alexander Shishkin
  Cc: Al.Grant, coresight, Leo Yan, Sudeep Holla, linux-arm-kernel, Mike Leach

Some hardware will ignore bit TRCPDCR.PU which is used to signal
to hardware that power should not be removed from the trace unit.
Let's mitigate against this by conditionally saving and restoring
the trace unit state when the CPU enters low power states.

This patchset introduces a firmware property named
'arm,coresight-needs-save-restore' - when this is present the
hardware state will be conditionally saved and restored.

A module parameter 'pm_save_enable' is also introduced which can
be configured to override the firmware property.

The hardware state is only ever saved and restored when a self-hosted
coresight is in use.

Changes since v3:

 - Only save/restore when self-hosted is being used and detect this
   without relying on the coresight registers (which may not be
   available)

 - Only allocate memory for etmv4_save_state at probe time when
   configuration indicates it may be used

 - Set pm_save_enable param to 0444 such that it is static after
   boot

 - Save/restore TRCPDCR

 - Add missing comments to struct etm4_drvdata documentation

 - Rebased onto coresight/next (8f1f9857)

Changes since v2:

 - Move the PM notifier block from drvdata to file static

 - Add section names to document references

 - Add additional information to commit messages

 - Remove trcdvcvr and trcdvcmr from saved state and add a comment to
   describe why

 - Ensure TRCPDCR_PU is set after restore and add a comment to explain
   why we bother toggling TRCPDCR_PU on save/restore

 - Reword the pm_save_enable options and add comments

 - Miscellaneous style changes

 - Move device tree binding documentation to its own patch

Changes since v1:

 - Rebased onto coresight/next

 - Correcly pass bit number rather than BIT macro to coresight_timeout

 - Abort saving state if a timeout occurs

 - Fix completely broken pm_notify handling and unregister handler on error

 - Use state_needs_restore to ensure state is restored only once

 - Add module parameter description to existing boot_enable parameter
   and use module_param instead of module_param_named

 - Add firmware bindings for coresight-needs-save-restore

 - Rename 'disable_pm_save' to 'pm_save_enable' which allows for
   disabled, enabled or firmware

 - Update comment on etm4_os_lock, it incorrectly indicated that
   the code unlocks the trace registers

 - Add comments to explain use of OS lock during save/restore

 - Fix incorrect error description whilst waiting for PM stable

 - Add WARN_ON_ONCE when cpu isn't as expected during save/restore

 - Various updates to commit messages


Andrew Murray (6):
  coresight: etm4x: remove superfluous setting of os_unlock
  coresight: etm4x: use explicit barriers on enable/disable
  coresight: etm4x: use module_param instead of module_param_named
  coresight: etm4x: improve clarity of etm4_os_unlock comment
  coresight: etm4x: save/restore state across CPU low power states
  dt-bindings: arm: coresight: Add support for
    coresight-needs-save-restore

 .../devicetree/bindings/arm/coresight.txt     |   3 +
 drivers/hwtracing/coresight/coresight-etm4x.c | 346 +++++++++++++++++-
 drivers/hwtracing/coresight/coresight-etm4x.h |  64 ++++
 3 files changed, 406 insertions(+), 7 deletions(-)

-- 
2.21.0


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2019-07-30 12:51 [PATCH v4 0/6] coresight: etm4x: save/restore ETMv4 context across CPU low power states Andrew Murray
2019-07-30 12:51 ` [PATCH v4 1/6] coresight: etm4x: remove superfluous setting of os_unlock Andrew Murray
2019-07-30 12:51 ` [PATCH v4 2/6] coresight: etm4x: use explicit barriers on enable/disable Andrew Murray
2019-08-01 13:31   ` Sasha Levin
2019-08-01 14:48     ` Mathieu Poirier
2019-08-02 18:08   ` Sasha Levin
2019-07-30 12:51 ` [PATCH v4 3/6] coresight: etm4x: use module_param instead of module_param_named Andrew Murray
2019-08-02 10:23   ` Suzuki K Poulose
2019-07-30 12:51 ` [PATCH v4 4/6] coresight: etm4x: improve clarity of etm4_os_unlock comment Andrew Murray
2019-07-30 12:51 ` [PATCH v4 5/6] coresight: etm4x: save/restore state across CPU low power states Andrew Murray
2019-07-30 21:16   ` Mathieu Poirier
2019-07-30 21:45     ` Andrew Murray
2019-07-31  8:16       ` Mike Leach
2019-07-31  9:45         ` Andrew Murray
2019-08-02 10:54   ` Suzuki K Poulose
2019-08-14  9:12     ` Andrew Murray
2019-07-30 12:51 ` [PATCH v4 6/6] dt-bindings: arm: coresight: Add support for coresight-needs-save-restore Andrew Murray
2019-08-02 10:40   ` Suzuki K Poulose
2019-08-02 14:37     ` Andrew Murray
2019-08-04 13:13       ` Mathieu Poirier
2019-08-14 10:01         ` Andrew Murray
2019-08-14 11:06           ` Mike Leach
2019-08-14 12:35             ` Suzuki K Poulose
2019-08-14 12:49               ` Andrew Murray
2019-08-14 14:20               ` Mike Leach
2019-07-30 20:12 ` [PATCH v4 0/6] coresight: etm4x: save/restore ETMv4 context across CPU low power states Mathieu Poirier
2019-07-30 21:46   ` Andrew Murray

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