From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: Andrew Murray <andrew.murray@arm.com>
Cc: Al.Grant@arm.com, Suzuki K Poulose <suzuki.poulose@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
coresight@lists.linaro.org, Sudeep Holla <sudeep.holla@arm.com>,
Leo Yan <leo.yan@linaro.org>,
linux-arm-kernel@lists.infradead.org,
Mike Leach <mike.leach@linaro.org>
Subject: Re: [PATCH v4 0/6] coresight: etm4x: save/restore ETMv4 context across CPU low power states
Date: Tue, 30 Jul 2019 14:12:20 -0600 [thread overview]
Message-ID: <20190730201220.GA4878@xps15> (raw)
In-Reply-To: <20190730125157.884-1-andrew.murray@arm.com>
Hi Andrew,
On Tue, Jul 30, 2019 at 01:51:51PM +0100, Andrew Murray wrote:
> 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
I have picked up the first 4 patches, so no need to send them with your next
revision. Note that for patch 2/6 I have removed the "stable" tag as the patch
doesn't apply to any of the stable tree. Since I have another one like that in
my tree I will rework both patches and send them directly to Greg for stable
consideration.
Thanks,
Mathieu
> 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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next prev parent reply other threads:[~2019-07-30 20:12 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
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 ` Mathieu Poirier [this message]
2019-07-30 21:46 ` [PATCH v4 0/6] coresight: etm4x: save/restore ETMv4 context across CPU low power states Andrew Murray
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