Re: [PATCH v2 12/13] iommu/rockchip: Add runtime PM support

Tomasz Figa
2018-01-17T06:20:30Z

On Tue, Jan 16, 2018 at 10:25 PM, Jeffy Chen <jeffy.chen-TNX95d0MmH7DzftRWevZcw@public.gmane.org> wrote:
> When the power domain is powered off, the IOMMU cannot be accessed and
> register programming must be deferred until the power domain becomes
> enabled.
>
> Add runtime PM support, and use runtime PM device link from IOMMU to
> master to startup and shutdown IOMMU.
[snip]
> @@ -875,28 +889,19 @@ static size_t rk_iommu_unmap(struct iommu_domain *domain, unsigned long _iova,
>
> static struct rk_iommu *rk_iommu_from_dev(struct device *dev)
> {
> - return dev->archdata.iommu;
> + struct rk_iommudata *data = dev->archdata.iommu;
> +
> + return data ? data->iommu : NULL;
> }

Is this change intentionally added to this patch? I see this
potentially relevant for the previous patch in this series.

[snip]
> +static int rk_iommu_startup(struct rk_iommu *iommu)
> {
> - struct rk_iommu *iommu;
> + struct iommu_domain *domain = iommu->domain;
> struct rk_iommu_domain *rk_domain = to_rk_domain(domain);
> - unsigned long flags;
> int ret, i;
>
> - /*
> - * Allow 'virtual devices' (e.g., drm) to attach to domain.
> - * Such a device does not belong to an iommu group.
> - */
> - iommu = rk_iommu_from_dev(dev);
> - if (!iommu)
> - return 0;
> -
> - if (iommu->domain)
> - rk_iommu_detach_device(iommu->domain, dev);
> -
> ret = rk_iommu_enable_clocks(iommu);
> if (ret)
> return ret;
>

Don't we need to check here (and in _shutdown() too) if we have a
domain attached?

> + mutex_lock(&iommu->pm_mutex);
> ret = rk_iommu_enable_stall(iommu);
> if (ret)
> - goto err_disable_clocks;
> + goto err_unlock_mutex;
[snip]
> + iommu->domain = NULL;
> +
> + spin_lock_irqsave(&rk_domain->iommus_lock, flags);
> + list_del_init(&iommu->node);
> + spin_unlock_irqrestore(&rk_domain->iommus_lock, flags);
> +
> + if (pm_runtime_get_if_in_use(iommu->dev) > 0) {

Actually, if the above call returns -EINVAL, don't we still need to
call rk_iommu_shutdown(), because it just means runtime PM is disabled
and the IOMMU is always powered on?

> + rk_iommu_shutdown(iommu);
> + pm_runtime_put(iommu->dev);
> + }
> +}
[snip]
> + spin_lock_irqsave(&rk_domain->iommus_lock, flags);
> + list_add_tail(&iommu->node, &rk_domain->iommus);
> + spin_unlock_irqrestore(&rk_domain->iommus_lock, flags);
> +
> + if (pm_runtime_get_if_in_use(iommu->dev) <= 0)

Ditto.

> + return 0;
> +
> + ret = rk_iommu_startup(iommu);
> + if (ret)
> + rk_iommu_detach_device(data->domain, dev);
[snip]
> @@ -1108,7 +1175,9 @@ static int rk_iommu_of_xlate(struct device *dev,
> return -ENODEV;
> }
>
> - dev->archdata.iommu = platform_get_drvdata(iommu_dev);
> + data->iommu = platform_get_drvdata(iommu_dev);
> + dev->archdata.iommu = data;
> +

I think this change might be mistakenly squashed to this patch instead
of previous.

Best regards,
Tomasz