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SubjectRe: [PATCH v12 3/4] iommu/arm-smmu: Add the device_link between masters and smmu
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On Sunday, July 8, 2018 7:34:12 PM CEST Vivek Gautam wrote:
> From: Sricharan R <sricharan@codeaurora.org>
>
> Finally add the device link between the master device and
> smmu, so that the smmu gets runtime enabled/disabled only when the
> master needs it. This is done from add_device callback which gets
> called once when the master is added to the smmu.
>
> Signed-off-by: Sricharan R <sricharan@codeaurora.org>
> Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
> Reviewed-by: Tomasz Figa <tfiga@chromium.org>
> Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
> Cc: Lukas Wunner <lukas@wunner.de>
> ---
>
> - Change since v11
> * Replaced DL_FLAG_AUTOREMOVE flag with DL_FLAG_AUTOREMOVE_SUPPLIER.
>
> drivers/iommu/arm-smmu.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 09265e206e2d..916cde4954d2 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -1461,8 +1461,20 @@ static int arm_smmu_add_device(struct device *dev)
>
> iommu_device_link(&smmu->iommu, dev);
>
> + if (pm_runtime_enabled(smmu->dev) &&

Why does the creation of the link depend on whether or not runtime PM
is enabled for the MMU device?

What about system-wide PM and system shutdown? Are they always guaranteed
to happen in the right order without the link?

> + !device_link_add(dev, smmu->dev,
> + DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER)) {
> + dev_err(smmu->dev, "Unable to add link to the consumer %s\n",
> + dev_name(dev));
> + ret = -ENODEV;
> + goto out_unlink;
> + }
> +
> return 0;
>
> +out_unlink:
> + iommu_device_unlink(&smmu->iommu, dev);
> + arm_smmu_master_free_smes(fwspec);
> out_cfg_free:
> kfree(cfg);
> out_free:
>


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