Hi Joerg,

On Tue, Mar 22, 2016 at 06:58:29PM +0100, Joerg Roedel wrote:
> From: Joerg Roedel <[email protected]>
> 
> Remove the usage of of_parse_phandle_with_args() and replace
> it by the phandle-iterator implementation so that we can
> parse out all of the potentially present 128 stream-ids.
> 
> Signed-off-by: Joerg Roedel <[email protected]>
> ---
>  drivers/iommu/arm-smmu.c | 28 ++++++++++++++++++++++------
>  1 file changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 59ee4b8..413bd64 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -48,7 +48,7 @@
>  #include "io-pgtable.h"
>  
>  /* Maximum number of stream IDs assigned to a single device */
> -#define MAX_MASTER_STREAMIDS         MAX_PHANDLE_ARGS
> +#define MAX_MASTER_STREAMIDS         128
>  
>  /* Maximum number of context banks per SMMU */
>  #define ARM_SMMU_MAX_CBS             128
> @@ -349,6 +349,12 @@ struct arm_smmu_domain {
>       struct iommu_domain             domain;
>  };
>  
> +struct arm_smmu_phandle_args {
> +     struct device_node *np;
> +     int args_count;
> +     uint32_t args[MAX_MASTER_STREAMIDS];
> +};
> +
>  static struct iommu_ops arm_smmu_ops;
>  
>  static DEFINE_SPINLOCK(arm_smmu_devices_lock);
> @@ -458,7 +464,7 @@ static int insert_smmu_master(struct arm_smmu_device 
> *smmu,
>  
>  static int register_smmu_master(struct arm_smmu_device *smmu,
>                               struct device *dev,
> -                             struct of_phandle_args *masterspec)
> +                             struct arm_smmu_phandle_args *masterspec)
>  {
>       int i;
>       struct arm_smmu_master *master;
> @@ -1716,7 +1722,8 @@ static int arm_smmu_device_dt_probe(struct 
> platform_device *pdev)
>       struct arm_smmu_device *smmu;
>       struct device *dev = &pdev->dev;
>       struct rb_node *node;
> -     struct of_phandle_args masterspec;
> +     struct of_phandle_iterator it;
> +     struct arm_smmu_phandle_args masterspec;
>       int num_irqs, i, err;
>  
>       smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL);
> @@ -1777,9 +1784,14 @@ static int arm_smmu_device_dt_probe(struct 
> platform_device *pdev)
>  
>       i = 0;
>       smmu->masters = RB_ROOT;
> -     while (!of_parse_phandle_with_args(dev->of_node, "mmu-masters",
> -                                        "#stream-id-cells", i,
> -                                        &masterspec)) {
> +
> +     of_for_each_phandle(&it, err, dev->of_node,
> +                         "mmu-masters", "#stream-id-cells", 0) {
> +             int count = of_phandle_iterator_args(&it, masterspec.args,
> +                                                  MAX_MASTER_STREAMIDS);
> +             masterspec.np           = of_node_get(it.node);
> +             masterspec.args_count   = count;
> +
>               err = register_smmu_master(smmu, dev, &masterspec);
>               if (err) {
>                       dev_err(dev, "failed to add master %s\n",
> @@ -1789,6 +1801,10 @@ static int arm_smmu_device_dt_probe(struct 
> platform_device *pdev)
>  
>               i++;
>       }
> +
> +     if (i == 0)
> +             goto out_put_masters;

I'm confused by this hunk. If i == 0, then we shouldn't have registered
any masters and therefore out_put_masters won't have anything to do.

In fact, I'm not completely clear on how the of_node refcounting interacts
with your iterators. Does the iterator put the node after you call the
"next" function, or does it increment each thing exactly once?

Will
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