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a6943befb9
Issue: 1. On arm32 platform iommu use the mapping->domain, while use the group->domain on arm64 platform. 2. __iommu_attach_group use group->default to judge whether new device in kernel 5.10 branch, while use group->domain in kernel 6.1 branch. For this change, when two devices share the iommu, the first device attach success, while the second device failed in kernel 6.1 branch. Method: 1. Set driver_managed_dma=true to ensure that during the IOMMU probe phase, even if attach group failed, the mapping will not be released. 2. After the IOMMU probe succeeds, record info->domain=mapping->domain and detach it, ensuring that group->domain is set to NULL. This prevents the next device which sharing the IOMMU, not return -EBUSY when attach the group. 3. Before hardware running, the shared IOMMU should check whether the device has been switched. If so, it needs to attach the current device's info->domain. 4. When removing a shared IOMMU, it must also ensure that group->domain corresponds to the current device. Change-Id: If0fec01a0bcf9c49850129bfa5ac28484fece9a2 Signed-off-by: Ding Wei <leo.ding@rock-chips.com>
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.