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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 prepare a iommu group(domain) for each a iova range
requirement.
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
add this:
/*
* iova start at 0x1_0000_0000, pa still start at 0x4000_0000
* size is 0x1_0000_0000.
*/
dma-ranges = <0x1 0x0 0x0 0x40000000 0x1 0x0>; /* 4G ~ 8G */
Note: we don't have a actual bus concept here. the master doesn't have its
special parent node, thus this dma-ranges can only be put in the master's
node.
b) Update the dma_mask:
dma_set_mask_and_coherent(dev, DMA_BIT_MASK(33));
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20210111111914.22211-29-yong.wu@mediatek.com
Signed-off-by: Will Deacon <will@kernel.org>
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.