Re: [PATCH 2/3] iommu: mediatek: Add support of unmanaged iommu domain

[Robin Murphy <robin.murphy@arm.com>]

On 2023-01-30 10:27, Alexandre Bailon wrote:
> Currently, the driver can allocate an unmanaged iommu domain.
> But, this only works for SoC having multiple bank or multiple iova region.

That is for good reason - there is only a single pagetable per bank, so 
if there are multiple devices assigned to a single bank, they cannot 
possibly be attached to different domains at the same time. Hence why 
the banks are modelled as groups.

Thanks,
Robin.

> This updates the driver to also support unmanaged iommu domain if
> MTK_UNMANAGED_DEVICE is set in the iommu id.
> 
> Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
> ---
>   drivers/iommu/mtk_iommu.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 2badd6acfb23d..5884a1ad409a0 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -858,9 +858,15 @@ static int mtk_iommu_get_group_id(struct device *dev, const struct mtk_iommu_pla
>   static struct iommu_group *mtk_iommu_device_group(struct device *dev)
>   {
>   	struct mtk_iommu_data *c_data = dev_iommu_priv_get(dev), *data;
> +	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
>   	struct list_head *hw_list = c_data->hw_list;
>   	struct iommu_group *group;
>   	int groupid;
> +	int i;
> +
> +	for (i = 0; i < fwspec->num_ids; i++)
> +		if (MTK_M4U_UNMANAGED(fwspec->ids[i]))
> +			return iommu_group_alloc();
>   
>   	data = mtk_iommu_get_frst_data(hw_list);
>   	if (!data)