On Sat, Jul 11, 2020 at 02:48:43PM +0800, Yong Wu wrote:

Some HW IP(ex: CCU) require the special iova range. That means the
iova got from dma_alloc_attrs for that devices must locate in his
special range. In this patch, we allocate a special iova_range for
each a special requirement and create each a iommu domain for each
a iova_range.

meanwhile we still use one pagetable which support 16GB iova.

After this patch, If the iova range of a master is over 4G, the master
should:
a) Declare its special dma_ranges in its dtsi node. For example, If we
preassign the iova 4G-8G for vcodec, then the vcodec dtsi node should:
	dma-ranges = <0x1 0x0 0x1 0x0 0x1 0x0>;  /* 4G ~ 8G */

BTW, dma-ranges should be in the parent node of the vcodec.

b) Update the dma_mask:
 dma_set_mask_and_coherent(dev, DMA_BIT_MASK(33));

This should happen for you automatically. The DMA PFN offset 
should also be 4GB here.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
---
 drivers/iommu/mtk_iommu.c | 49 ++++++++++++++++++++++++++++++++-------
 drivers/iommu/mtk_iommu.h |  3 ++-
 2 files changed, 42 insertions(+), 10 deletions(-)