Re: [PATCH v2 13/22] iommu/tegra: smmu: Create default IOVA maps

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 07/29/2013 05:24 AM, Hiroshi Doyu wrote:
> Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> wrote @ Thu, 18 Jul 2013 22:10:29 +0200:
> 
>> On 07/05/2013 04:44 AM, Hiroshi Doyu wrote:
>>> Create default IOVA maps at boot-up which can be attached to devices.
>>
>>> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
>>
>>>  static int tegra_smmu_probe(struct platform_device *pdev)
>>>  {
>>>  	struct smmu_device *smmu;
>>
>>> @@ -1160,13 +1182,15 @@ static int tegra_smmu_probe(struct platform_device *pdev)
>>>  	if (of_property_read_u32(dev->of_node, "nvidia,#asids", &asids))
>>>  		return -ENODEV;
>>>  
>>> -	bytes = sizeof(*smmu) + asids * sizeof(*smmu->as);
>>> +	bytes = sizeof(*smmu) + asids * (sizeof(*smmu->as) +
>>> +					 sizeof(struct dma_iommu_mapping *));
>>>  	smmu = devm_kzalloc(dev, bytes, GFP_KERNEL);
>>>  	if (!smmu) {
>>>  		dev_err(dev, "failed to allocate smmu_device\n");
>>>  		return -ENOMEM;
>>>  	}
>>>  
>>> +	smmu->map = (struct dma_iommu_mapping **)(smmu->as + asids);
>>
>> Shouldn't "+ asids" be "+ asids * sizeof(*smmu->as)" to match the
>> calculation of "bytes" above?
> 
> The structure is:
> 
> smmu {
>      ....
>      struct dma_iommu_mapping **map;
>      ....	
>      struct smmu_as	as[0];
> };
> 
> I think that this is correct, but is the following better?

Oh right, I guess since that's pointer-math, the compiler already
multiplies by the array entry size.

> + smmu->map = (struct dma_iommu_mapping **)&smmu->as[asids];

That would be a bit more obvious.