Subject: [PATCH v5 2/2] iommu/exynos: Add iommu driver for Exynos Platforms

From: [email-masked] (Roedel, Joerg)
Date: Fri, 14 Oct 2011 16:17:14 +0200

On Thu, Oct 13, 2011 at 04:13:23AM -0400, KyongHo Cho wrote:
> +struct exynos_iommu_domain {
> +       struct device *dev;
> +       unsigned long *pgtable;
> +       spinlock_t lock;
> +       spinlock_t pgtablelock;
> +};

Can you please add comments to document what these spinlocks protect?

> +static int exynos_iommu_attach_device(struct iommu_domain *domain,
> +                                  struct device *dev)
> +{
> +       struct exynos_iommu_domain *priv = domain->priv;
> +       int ret;
> +
> +       spin_lock(&priv->lock);
> +
> +       priv->dev = dev;
> +
> +       spin_unlock(&priv->lock);
> +
> +       ret = exynos_iommu_enable(domain);
> +
> +       return ret;
> +}
> +
> +static void exynos_iommu_detach_device(struct iommu_domain *domain,
> +                                   struct device *dev)
> +{
> +       struct exynos_iommu_domain *priv = domain->priv;
> +
> +       spin_lock(&priv->lock);
> +
> +       if (priv->dev == dev) {
> +               priv->dev = NULL;
> +
> +               spin_unlock(&priv->lock);
> +
> +               exynos_iommu_disable(domain);
> +       } else {
> +               spin_unlock(&priv->lock);
> +       }
> +}

That looks weird. As I read this code there is a 1-1 mapping between a
device and a domain. This breaks semantics of the iommu-api where a
domain can contain multiple devices.

	Joerg

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