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SubjectRe: [PATCH v13 0/4] iommu/arm-smmu: Add runtime pm/sleep support
On Thu, Jul 19, 2018 at 3:45 PM, Vivek Gautam
<vivek.gautam@codeaurora.org> wrote:
> This series provides the support for turning on the arm-smmu's
> clocks/power domains using runtime pm. This is done using
> device links between smmu and client devices. The device link
> framework keeps the two devices in correct order for power-cycling
> across runtime PM or across system-wide PM.
>
> With addition of a new device link flag DL_FLAG_AUTOREMOVE_SUPPLIER [8]
> (available in linux-next of Rafael's linux-pm tree [9]), the device links
> created between arm-smmu and its clients will be automatically purged
> when arm-smmu driver unbinds from its device.
>
> As not all implementations support clock/power gating, we are checking
> for a valid 'smmu->dev's pm_domain' to conditionally enable the runtime
> power management for such smmu implementations that can support it.
> Otherwise, the clocks are turned to be always on in .probe until .remove.
> With conditional runtime pm now, we avoid touching dev->power.lock
> in fastpaths for smmu implementations that don't need to do anything
> useful with pm_runtime.
> This lets us to use the much-argued pm_runtime_get_sync/put_sync()
> calls in map/unmap callbacks so that the clients do not have to
> worry about handling any of the arm-smmu's power.
>
> This series also adds support for Qcom's arm-smmu-v2 variant that
> has different clocks and power requirements.
>
> Previous version of this patch series is @ [2].
>
> Tested this series on msm8996, and sdm845 after pulling in Rafael's linux-pm
> linux-next[9] and Joerg's iommu next[10] branches.

Hi Rafael,

If the changes look good to you now, can you please consider giving your Ack.
Thanks.

Hi Robin, Will,
If the series looks good to you, and if there's a chance, can you
please consider
picking this series for 4.19. Thanks.

Best regards
Vivek

>
> [v13]
> Addressing Rafael's comments:
> * Added .suspend pm callback to disable the clocks in system wide suspend.
> * Added corresponding clock enable in .resume pm callback.
> * Explicitly enabling/disabling the clocks now when runtime PM is disabled.
> * device_link_add() doesn't depend on pm_runtime_enabled() as we can
> use device links across system suspend/resume too.
>
> Addressing Robin's comments:
> * Making device_link_add failures as non-fatal.
>
> * Removed IOMMU_OF_DECLARE() declaration as we don't need this after Rob's
> patch that removed all of these declarations.
>
> [v12]
> * Use new device link's flag introduced in [8] -
> DL_FLAG_AUTOREMOVE_SUPPLIER. With this devices links are automatically
> purged when arm-smmu driver unbinds.
> * Using pm_runtime_force_suspend() instead of pm_runtime_disable() to
> avoid following warning from arm_smmu_device_remove()
>
> [295711.537507] ------------[ cut here ]------------
> [295711.544226] Unpreparing enabled smmu_mdp_ahb_clk
> [295711.549099] WARNING: CPU: 0 PID: 1 at ../drivers/clk/clk.c:697
> clk_core_unprepare+0xd8/0xe0
> ...
> [295711.674073] Call trace:
> [295711.679454] clk_core_unprepare+0xd8/0xe0
> [295711.682059] clk_unprepare+0x28/0x40
> [295711.685964] clk_bulk_unprepare+0x28/0x40
> [295711.689701] arm_smmu_device_remove+0x88/0xd8
> [295711.693692] arm_smmu_device_shutdown+0xc/0x18
> [295711.698120] platform_drv_shutdown+0x20/0x30
>
> [v11]
> * Some more cleanups for device link. We don't need an explicit
> delete for device link from the driver, but just set the flag
> DL_FLAG_AUTOREMOVE.
> device_link_add() API description says -
> "If the DL_FLAG_AUTOREMOVE is set, the link will be removed
> automatically when the consumer device driver unbinds."
> * Addressed the comments for 'smmu' in arm_smmu_map/unmap().
> * Dropped the patch [7] that introduced device_link_del_dev() API.
>
> [v10]
> * Introduce device_link_del_dev() API to delete the link between
> given consumer and supplier devices. The users of device link
> do not need to store link pointer to delete the link later.
> They can straightaway use this API by passing consumer and
> supplier devices.
> * Made corresponding changes to arm-smmu driver patch handling the
> device links.
> * Dropped the patch [6] that was adding device_link_find() API to
> device core layer. device_link_del_dev() serves the purpose to
> directly delete the link between two given devices.
>
> [v9]
> * Removed 'rpm_supported' flag, instead checking on pm_domain
> to enable runtime pm.
> * Creating device link only when the runtime pm is enabled, as we
> don't need a device link besides managing the power dependency
> between supplier and consumer devices.
> * Introducing a patch to add device_link_find() API that finds
> and existing link between supplier and consumer devices.
> Also, made necessary change to device_link_add() to use this API.
> * arm_smmu_remove_device() now uses this device_link_find() to find
> the device link between smmu device and the master device, and then
> delete this link.
> * Dropped the destroy_domain_context() fix [5] as it was rather,
> introducing catastrophically bad problem by destroying
> 'good dev's domain context.
> * Added 'Reviwed-by' tag for Tomasz's review.
>
> [v8]
> * Major change -
> - Added a flag 'rpm_supported' which each platform that supports
> runtime pm, can enable, and we enable runtime_pm over arm-smmu
> only when this flag is set.
> - Adding the conditional pm_runtime_get/put() calls to .map, .unmap
> and .attach_dev ops.
> - Dropped the patch [3] that exported pm_runtim_get/put_suupliers(),
> and also dropped the user driver patch [4] for these APIs.
>
> * Clock code further cleanup
> - doing only clk_bulk_enable() and clk_bulk_disable() in runtime pm
> callbacks. We shouldn't be taking a slow path (clk_prepare/unprepare())
> from these runtime pm callbacks. Thereby, moved clk_bulk_prepare() to
> arm_smmu_device_probe(), and clk_bulk_unprepare() to
> arm_smmu_device_remove().
> - clk data filling to a common method arm_smmu_fill_clk_data() that
> fills the clock ids and number of clocks.
>
> * Addressed other nits and comments
> - device_link_add() error path fixed.
> - Fix for checking negative error value from pm_runtime_get_sync().
> - Documentation redo.
>
> * Added another patch fixing the error path in arm_smmu_attach_dev()
> to destroy allocated domain context.
>
> [v7]
> * Addressed review comments given by Robin Murphy -
> - Added device_link_del() in .remove_device path.
> - Error path cleanup in arm_smmu_add_device().
> - Added pm_runtime_get/put_sync() in .remove path, and replaced
> pm_runtime_force_suspend() with pm_runtime_disable().
> - clk_names cleanup in arm_smmu_init_clks()
> * Added 'Reviewed-by' given by Rob H.
>
> ** Change logs for previous versions is available in last series [4].
>
>
> [1] https://patchwork.kernel.org/patch/10204925/
> [2] https://lkml.org/lkml/2018/7/8/124
> [3] https://patchwork.kernel.org/patch/10204945/
> [4] https://patchwork.kernel.org/patch/10204925/
> [5] https://patchwork.kernel.org/patch/10254105/
> [6] https://patchwork.kernel.org/patch/10277975/
> [7] https://patchwork.kernel.org/patch/10281613/
> [8] https://patchwork.kernel.org/patch/10491481/
> [9] https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git/log/?h=linux-next
> [10] https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git/log/?h=next
>
> Sricharan R (3):
> iommu/arm-smmu: Add pm_runtime/sleep ops
> iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device
> iommu/arm-smmu: Add the device_link between masters and smmu
>
> Vivek Gautam (1):
> iommu/arm-smmu: Add support for qcom,smmu-v2 variant
>
> .../devicetree/bindings/iommu/arm,smmu.txt | 42 +++++
> drivers/iommu/arm-smmu.c | 192 +++++++++++++++++++--
> 2 files changed, 224 insertions(+), 10 deletions(-)
>
> --
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>
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> iommu@lists.linux-foundation.org
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