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

Hi Robin

On 1/30/23 13:04, Robin Murphy wrote:

On 2023-01-30 10:27, Alexandre Bailon wrote:

quoted

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.

I understand.
I am trying to upstream a remoteproc driver but the remote processor is
behind the iommu.
remoteproc can manage the iommu but it requires an unmanaged domain.
I tried a couple of things but this cause code duplication,
implies many hacks and not always reliable.
Do you have any suggestion ?

Thanks,
Alexandre

Thanks,
Robin.

quoted

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 <redacted>
---
  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)